refactor: drop 12 runtimes, keep Claude, Codex, OpenCode, Cursor, ZCode, Antigravity

Removes kilo, kimi, kimi-code, copilot, windsurf, augment, trae, qwen, hermes,
cline, codebuddy and pi end to end: capability descriptors, installer branches
and converters (bin/install.js 14.9k -> 11.2k lines), TypeScript converters,
hook surfaces and runtime homes, review lanes qwen/kimi-code, the two pi
migrations, Kimi payload normalization in the hook guards, dead hostBehaviors
vocabulary, launcher home probes, fixtures, runtime-specific tests and the
prose that presented them as supported.

Installer output for the six kept runtimes is byte-identical to before the
prune. The Kimi tool-vocabulary tests in workflow-guard, read-guard and
read-injection-scanner are left in place pending a decision.

scripts/lib/cli-exit.cjs

@@ -407,7 +407,7 @@ function runMain(main) {
  *   like `payload`. This exists because `hooks/msd-write-guard.js`'s
  *   emitBlock does NOT write the same bytes to both streams today — it
  *   writes the full JSON `output` to stdout but only the plain-text
- *   `output.reason` STRING to stderr, because Kimi's native hook bus reads
+ *   `output.reason` STRING to stderr, because a native hook bus may read
  *   stderr verbatim back to the model on exit 2. Migrating that call site
  *   onto terminateNow requires a way to say "fd 2 gets this different,
  *   plain-text value" — `stderrPayload` is that seam. Ignored entirely for