fix(#1821): stop copying dead hook scripts for Kilo and ZCode (hooksSurface:none)

Kilo and ZCode both declare `hooksSurface: 'none'` and have no plugin surface,
so the GSD installer staged lifecycle hook scripts (hooks/*.js, hooks/*.sh,
hooks/lib/) plus a `{"type":"commonjs"}` package.json marker into their config
dirs where nothing ever invokes them — dead weight (#1821).

The installer's two hook-copy guards at bin/install.js were still on the legacy
hardcoded runtime-name list and never excluded Kilo or ZCode. Add
`&& !isKilo && !isZcode` to both (isZcode added to the install() runtimeFlags
destructure).

OpenCode — which #1821 also named — is deliberately NOT excluded: since the
issue was filed, #1914 shipped a native OpenCode plugin (plugins/gsd-core.js)
that spawns those exact staged hooks via OpenCode's event bus and requires both
the hook scripts and the CommonJS package.json marker. Excluding OpenCode would
regress #1914, so its hooks stay live. The genuinely-dead cases are Kilo & ZCode.

- bin/install.js: add `&& !isKilo && !isZcode` to the hooks/dist copy guard and
  the hooks/lib copy guard; document the OpenCode-vs-Kilo/ZCode split.
- tests/install-minimal-hooks.test.cjs: regression test asserting Kilo and ZCode
  receive no gsd-*.js/.sh hooks or hooks/lib, while OpenCode keeps its hooks +
  #1914 plugin and Claude keeps its hooks (over-exclusion guard).
- tests/fixtures/golden-install-parity/{kilo,zcode}.json: drop the 21 hooks/*
  entries and the package.json marker they no longer receive (opencode unchanged).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/installer-migration-install.integration.test.cjs

@@ -35,12 +35,16 @@ const RUNTIME_INSTALL_CONTRACTS = {
   gemini: { surface: 'commands-gsd', settings: true, packageJson: true },
   hermes: { surface: 'hermes-skills', settings: true, packageJson: true },
   kimi: { surface: 'kimi-skills-agents', settings: false, packageJson: false },
-  kilo: { surface: 'flat-command', settings: false, packageJson: true },
+  // #1821: Kilo (hooksSurface:none, no plugin surface) no longer receives the
+  // dead hook scripts or the CommonJS package.json marker.
+  kilo: { surface: 'flat-command', settings: false, packageJson: false },
   opencode: { surface: 'flat-command', settings: true, packageJson: true },
   qwen: { surface: 'flat-skills', settings: true, packageJson: true },
   trae: { surface: 'flat-skills', settings: false, packageJson: false },
   windsurf: { surface: 'global-artifacts-noop', settings: false, packageJson: false },
-  zcode: { surface: 'flat-skills', settings: false, packageJson: true },
+  // #1821: ZCode (hooksSurface:none, no plugin surface) no longer receives the
+  // dead hook scripts or the CommonJS package.json marker.
+  zcode: { surface: 'flat-skills', settings: false, packageJson: false },
 };
 
 function sha256(content) {