fix: prevent PTY leak by detecting orphaned worker processes

When a tmux session is killed (e.g., via `tmux kill-session`), the
zshexit hook may not fire, leaving p10k worker and gitstatus daemon
processes orphaned (PPID=1). These orphaned processes hold PTY
resources indefinitely, eventually causing PTY exhaustion.

This fix adds parent process monitoring:

1. worker.zsh: Check PPID in main loop - exit if parent dies
2. gitstatus.plugin.zsh: Add background monitor that detects
   PPID change to 1 (init/launchd) and triggers cleanup

The fix handles the case where shells are terminated without
proper cleanup (SIGKILL, tmux kill-session, etc.).

Fixes orphaned processes like:
- p10k.worker.*.fifo holders
- gitstatus.POWERLEVEL9K.*.fifo holders
- gitstatusd-darwin-arm64 daemons

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

gitstatus/gitstatus.plugin.zsh

@@ -475,6 +475,21 @@ function _gitstatus_daemon"${1:-}"() {
       kill -- -$pgid
     fi
   } &!
+
+  # Parent process monitor: detect orphaning and cleanup
+  # This handles cases where zshexit hook doesn't fire (e.g., tmux kill-session)
+  {
+    local orig_ppid=$sysparams[ppid]
+    while true; do
+      command sleep 2
+      # If PPID changed to 1 (init/launchd), parent died - cleanup and exit
+      if [[ $sysparams[ppid] != $orig_ppid ]]; then
+        zf_rm -f -- $file_prefix.lock $file_prefix.fifo
+        kill -- -$pgid 2>/dev/null
+        break
+      fi
+    done
+  } &!
 }
 
 # Starts gitstatusd in the background. Does nothing and succeeds if gitstatusd is already running.