feat: add global loop tasks — dual ~/.pi-loop.json and local .pi-loop.json

[ta3pks]

Summary

Adds a global field to LoopTask. When true, the task persists to ~/.pi-loop.json instead of the CWD-based .pi-loop.json. The cron_create tool accepts a new optional global (boolean) parameter.

How it works

• Loading: On session_start, reads tasks from both {cwd}/.pi-loop.json (local) and ~/.pi-loop.json (global). No recursive tree walk — just two well-known locations.
• Dedup: When CWD == $HOME, the global path is skipped to avoid loading the same file twice.
• Writing: Tasks with global: true go to ~/.pi-loop.json; others go to {cwd}/.pi-loop.json. Empty files are cleaned up.
• Locking: Separate file locks (w/ stale-PID detection) for both local and global files.
• File watching: Both files are watched for external changes.

Changes

File	Change
src/types.ts	Added global?: boolean to LoopTask
src/store.ts	Dual-path loadDurableTasks / writeDurableTasks, isGlobal arg on acquireLock/releaseLock
src/index.ts	session_start loads from both paths and acquires both locks; session_shutdown releases both
src/tools/cron-tools.ts	cron_create accepts global param

Use case

cron_create {
  cron: "0 10 * * *",
  prompt: "morning check",
  durable: true,
  global: true
}

This task persists to ~/.pi-loop.json and fires regardless of which directory pi runs from.

[ta3pks]

👋 gentle bump — this has been tested and is working well on our end. Any interest in reviewing? Happy to address any feedback.