Clean up stale issue references in comments (gt-z5bri)

- daemon.go: Update gt-2hzl4 comment to past tense (timeout fallback is implemented)
- lifecycle.go: Remove "to be removed" promise for gt-psuw7 (code stays)
- keepalive_test.go: Remove tombstoned gt-gaxo epic reference
- doctor.go: Remove tombstoned gt-gaxo epic reference
- daemon_test.go: Remove tombstoned gt-gaxo epic reference

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/daemon/daemon.go

@@ -263,7 +263,7 @@ func (d *Daemon) ensureDeaconRunning() {
 	if beadErr == nil {
 		if beadState == "running" || beadState == "working" {
 			// Agent reports it's running - trust it
-			// Note: gt-2hzl4 will add timeout fallback for stale state
+			// Timeout fallback for stale state is in lifecycle.go
 			return
 		}
 	}