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/config-loader.test.cjs

@@ -1763,9 +1763,9 @@ describe('loadConfigResolved — runtime identity fill (#4717)', () => {
   test('MSD_RUNTIME outranks the marker in the identity fill (#4717)', (t) => {
     const projDir = mkTmp4717('msd-4717-proj-');
     t.after(() => cleanup4717(projDir));
-    process.env.MSD_RUNTIME = 'kimi';
+    process.env.MSD_RUNTIME = 'opencode';
     const resolved = loadConfigResolved(projDir, { persist: false });
-    assert.equal(resolved.config.runtime, 'kimi');
+    assert.equal(resolved.config.runtime, 'opencode');
   });
 
   // Branch D (the shared-defaults path) fires only when the project dir has NO