Prevent NotificationWatcher freezes and excessive energy use

[weimo123]

Problem

NotificationWatcher currently runs a recursive Accessibility-tree traversal from a repeating main-run-loop Timer every 1.5 seconds. Each element is queried through several synchronous cross-process AX calls.

This has two related failure modes:

• If Notification Center is slow or stops replying, the synchronous AX calls block the app main thread and the menu bar app becomes unresponsive until it is force-quit.
• Even while idle, the app repeatedly walks the Notification Center tree, causing unnecessary CPU wakeups and high cumulative energy impact.

A process sample of the released 1.0.0 build showed the timer callback on the main thread spending its active samples in NotificationWatcher.collectTexts and AXUIElementCopyAttributeValue IPC.

Changes

• Move all Notification Center discovery and AX traversal to a serial utility queue.
• Prefer AX created/window-created events and coalesce event bursts before scanning.
• Add a lightweight window-fingerprint fallback for macOS versions that do not expose those AX notifications.
• Avoid repeated full scans while the Notification Center window state is unchanged, with a 30-second safety scan.
• Set a 0.5-second AX messaging timeout so an unresponsive target cannot block indefinitely.
• Batch text and child attribute reads with AXUIElementCopyMultipleAttributeValues.
• Bound traversal depth and element count, and keep Notification Center restart and permission-loss handling.
• Add scan-throttling tests and bump the patch version to 1.0.1.

Validation

• make test: 39 passed, 0 failed
• NotificationWatcher sources compile with strict concurrency warnings treated as errors
• make app succeeds on macOS 15.7.9 / Apple Silicon
• Built app launches successfully and the packaged app passes deep strict codesign verification

The OTP extraction behavior itself is unchanged.