fix(#2305): stage the shared guard hooks Kilo's native plugin spawns (#2327)

* fix(#2305): stage shared guard hooks for Kilo — drop skipSharedHooksInstall

Kilo's capability descriptor declared BOTH hostBehaviors.nativePlugin (a
plugin that spawns the shared PreToolUse guard scripts as subprocesses)
AND hostBehaviors.skipSharedHooksInstall:true, which suppresses staging
of hooks/*.js into the Kilo config dir. The plugin's runHook treats an
absent hook script as a silent allow, so every guard it spawned
(gsd-prompt-guard, gsd-read-guard, gsd-worktree-path-guard) no-opped on
every Kilo install. OpenCode uses the byte-identical plugin with hook
staging on and is unaffected — it is the reference shape.

The skip flag predates Kilo's plugin surface: it dates to #1821 (hooks
were dead weight for a runtime with no hook consumer), and #2093 added
the hooks-dependent nativePlugin without revisiting it.

- capabilities/kilo/capability.json: remove skipSharedHooksInstall
  (regenerated gsd-core/bin/lib/capability-registry.cjs accordingly)
- bin/install.js: correct the stale #1821 comments claiming Kilo has no
  plugin surface
- tests/kilo-upgrades.test.cjs: install-fixture tests (global + local)
  asserting the guard scripts land where the plugin's walk-up resolves
  them; an end-to-end test driving a disallowed out-of-worktree write
  through the REAL installed Kilo tree and asserting the guard rejects
  it; a cross-runtime descriptor invariant (nativePlugin and
  skipSharedHooksInstall:true must never coexist)
- tests/kilo-imperative-reference.test.cjs: flip the pinned assertion
- golden fixtures regenerated (kilo now stages the 24 hook files, same
  set as OpenCode)

Fixes #2305

* fix(#2305): warn loudly when a guard hook script is missing (runHook)

runHook's absent-file branch returned a silent exit-0 allow — the
mechanism that let #2305 ship undetected: with the hooks bundle never
staged on Kilo, every PreToolUse guard the plugin spawned resolved to
"file not found → allow" with zero signal anywhere.

Keep the adapter's design contract (a missing hook must never break the
tool call — pinned by the existing adapter test) but make the absence
loud: console.error once per hook file, naming the unresolved path and
the remediation. Applied identically to .kilo/ and .opencode/ plugin
copies (byte-parity guard). Golden parity fixtures regenerated (the
installed plugin file's hash changed).

Fixes #2305

* chore(#2305): add changeset fragment

* test(#2305): include gsd-workflow-guard.js in the staged-guards regression list

The native plugin spawns four guards on write-like tool calls — the
regression test's PLUGIN_GUARD_HOOKS list covered three. Staging itself
was already asserted via the golden fixtures (the full bundle), but the
named per-guard assertion should cover every guard the plugin actually
dispatches. Surfaced by cross-AI review of PR #2327.

* test(#2305): update the #1821 tests that encoded Kilo's false no-plugin premise

The #1821 hook-copy test asserted Kilo must receive no staged hooks — the
exact behavior this PR reverses (and the cause of all 8 CI failures). Kilo
moves from the ZCode "no dead hooks" loop to the OpenCode group, with
positive assertions on the new contract: the three guard hooks the plugin
spawns, hooks/lib/git-cmd.js, and plugins/gsd-core.js all staged. The
integration runtime contract flips kilo packageJson to true (the CommonJS
marker ships with the bundle), and the pi contract comment no longer cites
Kilo as a no-plugin runtime.

* chore(#2305): scope the queued #1821 changeset fragment to ZCode only

The fragment still claimed the installer skips hooks for Kilo — rendering
both it and this PR's fragment into the same release would ship two
contradictory statements about Kilo's install behavior. It now claims
ZCode only and notes that #2327 reverses the Kilo half.

* chore(#2305): rename changeset fragment to the generator naming convention

2305-kilo-stage-guard-hooks.md -> loud-guard-hooks.md, matching the
<adjective>-<noun>-<noun> shape npm run changeset generates (review nit).

---------

Co-authored-by: Tom Boucher <trekkie@nomorestars.com>

.opencode/plugins/gsd-core.js

@@ -200,9 +200,23 @@ function mapToolInput(args) {
  * @param {string} [opts.cwd]         working directory for the child
  * @returns {{ stdout: string, exitCode: number, timedOut: boolean }}
  */
+const warnedMissingHooks = new Set();
+
 function runHook(hookFile, payload, opts = {}) {
   const hookPath = path.join(HOOKS_DIR, hookFile);
   if (!fs.existsSync(hookPath)) {
+    // A missing guard script means the guard is silently NOT enforced — the
+    // exact failure mode of #2305 (plugin staged, hooks bundle not). Never
+    // break the tool call (the adapter's design contract), but never be
+    // silent about it either: warn loudly, once per hook file.
+    if (!warnedMissingHooks.has(hookFile)) {
+      warnedMissingHooks.add(hookFile);
+      console.error(
+        `[gsd-core] hook script missing: ${hookPath} — ${hookFile} is NOT ` +
+          "enforced. The GSD install may be incomplete; reinstall (or run " +
+          "/gsd-update) to restage the hooks/ bundle.",
+      );
+    }
     return { stdout: "", exitCode: 0, timedOut: false };
   }
   const timeout = opts.timeout ?? 8000;