feat: restore daemon supervisor and remoteControlServer command (#170)

Reverse-engineer the missing daemon + remoteControlServer implementation
by tracing the call chain from existing code:

- src/daemon/main.ts: restore from stub to full supervisor (spawn/monitor
  workers, exponential backoff restart, graceful shutdown)
- src/daemon/workerRegistry.ts: restore from stub to worker dispatcher
  (remoteControl kind → runBridgeHeadless())
- src/commands/remoteControlServer/: new slash command /remote-control-server
  (alias /rcs) for managing the daemon from REPL
- build.ts + scripts/dev.ts: enable DAEMON feature flag

Both official CLI 2.1.92 and our codebase had the command registered in
commands.ts but the directory and daemon implementation were missing.
The bottom layer (runBridgeHeadless in bridgeMain.ts) was already complete.

Co-authored-by: unraid <local@unraid.local>

scripts/dev.ts

@@ -35,6 +35,8 @@ const DEFAULT_FEATURES = [
   // P1: API-dependent features
   "EXTRACT_MEMORIES", "VERIFICATION_AGENT",
   "KAIROS_BRIEF", "AWAY_SUMMARY", "ULTRAPLAN",
+  // P2: daemon + remote control server
+  "DAEMON",
 ];
 
 // Any env var matching FEATURE_<NAME>=1 will also enable that feature.