Remove Caps Lock control and optimize monitoring

[TW527E]

What changed

• remove the Caps Lock system preference controller, Settings checkbox, and menu item
• remove all Caps Lock documentation
• reduce the event-tap mask based on the enabled Shift and Shift-Space features
• rebuild the event tap safely when settings change or macOS disables it
• use one consistent TIS snapshot for each input-source notification
• refresh menu state when the menu opens

Why

The macOS Caps Lock preference could report disabled while the system still performed language switching, so the feature was not reliable enough to keep. The remaining changes improve stability, consistency, and idle event-processing overhead without adding polling.

Validation

• make test — 20 checks passed
• debug and release Swift builds passed
• real ABC-to-Apple-Pinyin source/layout confirmation passed
• dynamic event-monitor reconfiguration check passed
• application lifecycle and menu-bar smoke test passed
• local DMG verification passed

[Copilot]

Pull request overview

This PR removes the unreliable macOS Caps Lock language-switch integration and streamlines global input monitoring to be more stable and lower-overhead, while keeping the remaining Shift and Shift+Space features consistent across UI and notifications.

Changes:

• Remove the Caps Lock controller + all related UI (menu + Settings) and documentation.
• Reconfigure the global event tap to monitor only the event types required by currently enabled shortcuts, and rebuild safely when configuration changes or the tap is disabled.
• Use a single TIS “current input source” snapshot per notification to keep persistence, capability detection, and UI updates consistent; refresh menu state on open.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Sources/ShiftInput/StatusBarController.swift	Removes Caps Lock menu toggle and refreshes the “current source” menu item when the menu opens.
Sources/ShiftInput/PreferencesWindowController.swift	Removes the Caps Lock preference checkbox and related explanatory text; tightens window layout.
Sources/ShiftInput/InputSourceManager.swift	Uses one TIS snapshot per input-source notification to update persistence, capability detection, and UI consistently.
Sources/ShiftInput/GlobalKeyboardMonitor.swift	Introduces a configuration-driven event mask and rebuild logic to reduce monitored events and handle tap disablement.
Sources/ShiftInput/CapsLockLanguageSwitchController.swift	Deletes the Caps Lock system preference controller implementation.
Sources/ShiftInput/AppDelegate.swift	Removes Caps Lock wiring and rebuilds the keyboard monitor based on settings; rebuilds on tap disablement on main queue.
README.zh-CN.md	Removes Caps Lock docs; documents adaptive event mask and single-snapshot update behavior.
README.md	Removes Caps Lock docs; documents adaptive event mask and single-snapshot update behavior.
README.en.md	Removes Caps Lock docs; documents adaptive event mask and single-snapshot update behavior.

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