refactor(cli): migrate to citty — --help generated from flag definitions

Replace manual switch + HELP string with citty defineCommand/runMain.
Flag definitions in index.ts are now the single source of truth for
--help output. Remove parseArgs() from launch.ts; accept citty-parsed
flags + rawArgs (-- passthrough to claude preserved).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/cli/package.json

@@ -47,6 +47,7 @@
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "1.27.1",
+    "citty": "0.2.2",
     "libsodium-wrappers": "0.7.15",
     "ws": "8.20.0",
     "zod": "4.1.13"