enhance(#3587): add a per-phase commit_docs override (#3601)

* feat(#3587): add a per-phase commit_docs override

Delivers epic #2292's second user story: commit an architecture phase's
artifacts while execution phases stay local. commit_docs was project-wide and
binary, so the only choices were all phases or none.

Shape is a config dynamic key phase_commit_docs.<phase-id>, following the 14
existing dynamicKeyPatterns precedents rather than inventing a PLAN.md
frontmatter spec -- which #2292 itself flags as becoming its own maintenance
surface.

Tier 1 resolves in cmdCommit, NOT in loadConfig: loadConfig has no phase
context and is called by nearly every command, so threading one through it to
serve a single caller would be a far larger blast radius for no gain. The phase
comes from detectPhaseNumberFromFiles, which cmdCommit already computes for
branch naming and which is already hardened against the #2539 project-code bug.

Suppression by the per-phase tier returns its own reason rather than reusing
skipped_commit_docs_false -- telling a user their project setting is false when
it is true would be actively misleading. Additive; the two existing reason
strings that agents/gsd-executor.md matches on are unchanged.

The manifest's phase-id pattern is a hand-copy of PHASE_NUMBER_TOKEN_SOURCE
because the manifest is hand-maintained JSON, so a behavioral parity test
asserts both surfaces accept and reject the same token shapes.

* fix(#3587): fold tests, close review findings, update reference docs

Fold: the new tests were added as their own file, which required loosening a
grandfathered lint-test-file-count bucket 5-to-6. A ratchet exists to go down
only. commit-docs-bypass.test.cjs is the established commit_docs test home and
already hosts two folded suites, so the tests fold there as a third block and
the allowlist is reverted untouched.

Standards review: CONTEXT.md and the test header both cited a
phase-commit-docs-manifest-parity.test.cjs that never existed; a repo-wide
sweep found a fourth stale cite in the schema manifest description. All four
now name the real location.

Spec review: the issue's Scope of changes named planning-config.md and
git-planning-commit.md and neither was touched. Both now document the four-tier
precedence and the new skip reason.

Security review, minor and unproven: detectPhaseNumberFromFiles returns the
FIRST matching path's phase, so a --files list spanning two phases resolves the
override against whichever comes first. That helper is hardened and widely used,
so it is not changed; the behavior is pinned by a named test and disclosed in
the design and user docs. A pinned behavior is not a bug; an unpinned surprise
is.

* chore(#3587): backfill changeset pr number to 3601

---------

Co-authored-by: sim <sim@local>

gsd-core/references/git-planning-commit.md

@@ -12,7 +12,7 @@ Always use this for `.planning/` files — it handles `commit_docs` and gitignor
 gsd-tools query commit "docs({scope}): {description}" --files .planning/STATE.md .planning/ROADMAP.md
 ```
 
-The CLI will return `skipped` (with reason) if `commit_docs` is `false` or `.planning/` is gitignored. No manual conditional checks needed.
+The CLI will return `skipped` (with reason) if `commit_docs` is `false`, `.planning/` is gitignored, or a per-phase `phase_commit_docs.<phase-id>` override resolves `false` for the phase being committed. No manual conditional checks needed.
 
 ## Amend previous commit
 
@@ -37,4 +37,5 @@ gsd-tools query commit "" --files .planning/codebase/*.md --amend
 
 - `commit_docs: false` in config
 - `.planning/` is gitignored
+- `phase_commit_docs.<phase-id>` resolves `false` for the phase being committed — overrides the project-wide `commit_docs` for that phase only (reason `skipped_commit_docs_phase_false`)
 - No changes to commit (check with `git status --porcelain .planning/`)