fix(#2962): write npm-style gsd-sdk shim on Windows under --sdk install (#2971)

* fix(#2962): write npm-style gsd-sdk shim on Windows under --sdk install

trySelfLinkGsdSdk previously contained `if (process.platform === 'win32')
return null;` — a missed gap from #2775's POSIX self-link rather than an
intentional design choice. As a result, `npx get-shit-done-cc@latest
--claude --global --sdk` on Windows left `gsd-sdk` off PATH despite the
installer reporting success, and the obvious recovery (`npm i -g
@gsd-build/sdk`) lands the stale 0.1.0 publication that lacks the `query`
subcommand the agents call ~40 times.

This PR addresses the shim half. The npm-publish half (publishing
@gsd-build/sdk at parity with the get-shit-done-cc version) requires
maintainer credentials and is left for separate action.

Changes:

- bin/install.js: replace the unconditional Windows return-null with
  dispatch to a new trySelfLinkGsdSdkWindows() that:
  * resolves npm's global bin via `execFileSync('npm', ['prefix', '-g'])`
    (no shell interpolation; npm is the only PATH-resolved binary)
  * verifies write access with a probe before producing partial state
  * writes the standard npm shim triple to npm's global bin:
    - gsd-sdk.cmd (cmd.exe; CRLF line endings)
    - gsd-sdk.ps1 (PowerShell)
    - gsd-sdk    (Bash wrapper for Cygwin/MSYS/Git-Bash)
  * each shim invokes `node "<absolute path to bin/gsd-sdk.js>"` with the
    passed args, decoupling shim location from SDK location — same logical
    structure as the POSIX wrapper-via-require() fallback above
  * unlinks any stale shims before writing so prior installs don't pin
    callers to a now-absent path
  * returns the .cmd path on success (handle the existing onPath check
    looks for) or null on any failure, falling through to the existing
    "gsd-sdk is not on your PATH" warning at line 8704

- tests/bug-2962-windows-sdk-shim.test.cjs (new): 5 tests exercising
  trySelfLinkGsdSdkWindows directly with cp.execFileSync mocked to redirect
  npm prefix to a temp dir. Asserts shim contents reference the absolute
  path, .cmd uses CRLF, stale shims are replaced not appended, and null is
  returned when `npm prefix -g` fails.

- tests/no-unconditional-win32-skip.test.cjs (new): regression guard
  that fails CI if any future commit re-introduces
  `if (process.platform === 'win32') return null;` (or similar
  skip-only branches) in bin/install.js. Negative test verified by
  transiently re-introducing the bad pattern → guard fired → restored
  → passes.

Out of scope: publishing @gsd-build/sdk@<current> to npm so the natural
`npm i -g @gsd-build/sdk` recovery also lands a usable SDK. That requires
maintainer credentials and is the second half of the issue.

Closes #2962

* fix(#2962): address CodeRabbit findings — execSync for npm.cmd, behavior-based regression guard

CR finding 1 (🟠 Major): Node's child_process docs explicitly call out that
.cmd/.bat files cannot be spawned via execFile/execFileSync without a shell
("Spawning .bat and .cmd files on Windows" section). Since `npm` on Windows
is `npm.cmd`, my use of execFileSync('npm', ['prefix', '-g'], { shell: false })
would have failed on the very platform this PR is meant to fix.

Switched to cp.execSync('npm prefix -g', ...) — matching the existing
convention at line ~8718 which makes the same lookup. Args are static literals
so shell interpolation is not an injection vector.

CR finding 2 (🟠 Major): the source-grep regression test in
tests/no-unconditional-win32-skip.test.cjs violated the repo's no-source-grep
testing standard (CONTRIBUTING.md). Replaced with a behavior-based test that:

  - overrides process.platform to 'win32' via Object.defineProperty
  - mocks cp.execSync to return a temp-dir as npm prefix
  - calls trySelfLinkGsdSdk(shimSrc) and asserts it returns non-null AND
    materializes gsd-sdk.cmd on disk

The behavior guard is strictly stronger than the regex version: it would
catch any equivalent skip pattern (e.g. os.platform() === 'win32', a
typeof-based guard, etc.), not just literal `if (process.platform === 'win32')`
text. Negative-tested by re-introducing the `return null` skip → test fails
with maintainer-quoted diagnostic "trySelfLinkGsdSdk must not silently
return null on Windows; a no-op skip is a missed-parity regression"; restored
→ passes.

Test for Windows shim materialization (bug-2962-windows-sdk-shim.test.cjs)
also updated to mock cp.execSync (matching the new production code path)
instead of cp.execFileSync.

Full suite: 6480/6480 pass.

* test(#2962): make Windows shim tests self-contained per CR

Each test now invokes trySelfLinkGsdSdkWindows() itself before reading
the shim files, so they don't implicitly depend on the earlier test's
side effects. Addresses CR's order-dependence finding.

* test(#2962): structured shim parsing — eliminate substring source-grep

CR found that even after the prior refactor, three tests in the suite
still used .includes()/.startsWith() against shim file content
(cmdContent.includes(\`@node ${jsonQuoted} %*\`) etc.). Substring matching
on file text is the same anti-pattern the no-source-grep standard
forbids — even when the file is one this test wrote — because it asserts
a literal exists rather than that the structured shape is correct.

Replace with three small parsers (parseCmdShim, parsePs1Invocation,
parseBashInvocation) that split each shim into header + invocation
tokens and assert via deepEqual on structured records. The assertions
now check that the .cmd has @ECHO OFF / @SETLOCAL / @node <abs> %* in
that order with exactly 3 meaningful lines, and that the .ps1 and bash
wrappers split into the expected (call, nodeCmd, target, argToken)
tuples.

The stale-shim replacement test was hardened the same way: instead of
proving the absence of a sentinel substring, it now proves the parsed
target equals the new shimSrc and != the old path.

Verified: scripts/lint-no-source-grep.cjs reports 0 violations across
348 test files. The 6-test windows-sdk-shim + win32-skip-guard suite
all pass.

* fix(#2962): expose pure shim IR + tests assert on typed fields, not rendered text

Earlier "structured parser" approach (parseCmdShim / parsePs1Invocation /
parseBashInvocation) was still raw-text manipulation behind a function
wrapper — split('\\r\\n'), trim().split(/\\s+/), content.includes('\\r\\n').
Maintainer was right: hiding grep behind a parser is still grep.

Real fix: refactor production code to expose the structured intermediate
representation, and have tests assert on the IR fields directly.

Production:
- New buildWindowsShimTriple(shimSrc) — pure function, no fs/spawn.
  Returns { invocation: { interpreter, target }, eol: { cmd, ps1, sh },
  fileNames: { cmd, ps1, sh }, render: { cmd: () => string, ... } }.
  The IR is the contract; rendered text is an implementation detail of
  the renderers.
- trySelfLinkGsdSdkWindows now calls buildWindowsShimTriple, looks up
  filenames from triple.fileNames, and writes triple.render[kind]() to
  each target. Same observable behavior, structurally separated.
- buildWindowsShimTriple added to test-mode exports.

Tests (full rewrite — no shim file content is read at any point):
- Layer 1: pure-IR tests assert on triple.invocation.target,
  triple.eol === { cmd: '\\r\\n', ps1: '\\n', sh: '\\n' },
  triple.fileNames === { cmd: 'gsd-sdk.cmd', ... }, and the
  documented IR shape via Object.keys().sort() deepEqual.
- Layer 2: fs/spawn driver tests assert filesystem FACTS:
  - return value equals expected path
  - all three target files exist as regular non-empty files
  - rendered file byte length === Buffer.byteLength of triple.render(kind)
    output (proves the writer writes what the renderer produces, no
    mutation, no truncation, no double-write — without comparing content)
  - mtime advances on rewrite (proves stale-replace behavior)
  - returns null when npm prefix -g throws

No more split, .includes, .startsWith, .endsWith, or substring matching
anywhere in the test suite. Lint clean. 10/10 tests pass.

CHANGELOG.md

@@ -11,6 +11,7 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - **`gsd-sdk query agent-skills` emits raw `<agent_skills>` block instead of JSON-wrapped string** — workflows that embed via `$(gsd-sdk query agent-skills <agent>)` were receiving a JSON-quoted string literal mid-prompt (e.g. `"<agent_skills>\n…"`), silently breaking all `<agent_skills>` injection into spawned subagents. The CLI dispatcher now honors an opt-in `format: 'text'` field on `QueryResult` and writes such results raw via `process.stdout.write`; `--pick` always returns JSON regardless. (#2917)
 - **`sketch --wrap-up` now dispatches correctly** — `/gsd-sketch --wrap-up` was silently no-oping because the flag dispatch wiring was omitted when the micro-skill entry point was absorbed in #2790. (#2949)
 - **`help.md` no longer advertises eight slash commands removed by the #2824 consolidation** — `/gsd-do`, `/gsd-note`, `/gsd-check-todos`, `/gsd-plant-seed`, `/gsd-research-phase`, `/gsd-list-phase-assumptions`, `/gsd-plan-milestone-gaps`, and `/gsd-join-discord` were removed when 86 skills were folded into 59. `help.md` was not updated alongside, so users typing the documented commands hit *Unknown command*. Each entry is now either rewritten to the surviving flag-based dispatcher (e.g., `/gsd-do …` → `/gsd-progress --do "…"`, `/gsd-note` → `/gsd-capture --note`, `/gsd-plant-seed` → `/gsd-capture --seed`, `/gsd-check-todos` → `/gsd-capture --list`) or removed for skills with no replacement. A regression test now asserts every `/gsd-*` reference in `help.md` has a matching `commands/gsd/*.md` stub. (#2954)
+- **`--sdk` install on Windows now writes a callable `gsd-sdk` shim** — `npx get-shit-done-cc@latest --claude --global --sdk` on Windows previously left `gsd-sdk` off PATH because `trySelfLinkGsdSdk` returned `null` unconditionally on `win32` (a missed gap from #2775's POSIX self-link, not an intentional deferral). The function now dispatches to a Windows counterpart that writes the standard npm shim triple (`gsd-sdk.cmd`, `gsd-sdk.ps1`, and a Bash wrapper) to npm's global bin, so `gsd-sdk` resolves in a fresh shell across cmd.exe, PowerShell, and Cygwin/MSYS/Git-Bash. A new regression guard in `tests/no-unconditional-win32-skip.test.cjs` blocks any future `if (process.platform === 'win32') return null;` skip-only branches in `bin/install.js`. (#2962)
 
 ### Added — 1.40.0-rc.1
 - **Six namespace meta-skills with keyword-tag descriptions** — replace the flat 86-skill