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/gen-context-index.cjs

@@ -24,7 +24,7 @@
  * `--check`-guarded JSON manifest that is NOT runtime code. It previously
  * lived at msd-core/bin/lib/context-index.cjs — a shipped runtime module is
  * the wrong place for ~120 KB of arbitrary CONTEXT.md prose: it tripped both
- * tests/cline-install.test.cjs's leaked-`.claude`-path guard and
+ * the leaked-`.claude`-path guard and
  * tests/package-name-single-source.test.cjs's hardcoded-package-name guard,
  * both true positives against runtime-code content scanning. Moving the
  * artifact to docs/ (never scanned as runtime code) fixes both without