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.

tests/emitted-sizes.test.cjs

@@ -37,13 +37,13 @@ before(() => {
 });
 
 // ─── Shared real-install fixture (B1, B2, B7) ─────────────────────────────────
-// One windsurf global install, built once and shared read-only across the
+// One cursor global install, built once and shared read-only across the
 // assertions that need a REAL emitted tree — a shared FIXTURE, not shared
 // mutable state. Cleaned up in the top-level after().
 let fixture = null;
 
 before(() => {
-  const { configDir, root } = runMinimalInstall({ runtime: 'windsurf', scope: 'global' });
+  const { configDir, root } = runMinimalInstall({ runtime: 'cursor', scope: 'global' });
   fixture = { configDir, root };
 });