Add automatic lid control with keyboard dimming and lock-on-open

[ziyad-aljohani]

Normal idle-sleep prevention does not keep a Mac awake when its lid closes. This adds an Automatic lid control checkbox that follows Caffeine's existing activation toggle:

• Closing the lid sets the built-in display and keyboard brightness to zero while background work continues without requesting a lock.
• Opening the lid requests the native macOS lock. A black privacy cover stays in place and brightness remains zero until the session reports locked continuously for 750 ms, then the saved brightness levels return.
• Caffeine remains active after authentication for the next lid cycle. Unchecking the option keeps ordinary Caffeine available.
• At 10% battery or less while unplugged, Caffeine pauses quietly and resumes when external power is detected. It shows a specific battery reason in the menu/tooltip and manually opened preferences. Overheating has its own message and resumes after cooling. Neither pause opens preferences; manual deactivation and the original timer deadline cancel automatic resume. A pause during a protected lid cycle retains the cover and lock-on-open handling.

A limited privileged helper requests administrator approval on first installation and manages the system sleep override through a renewable lease. It restores ordinary sleep after deactivation, lease expiration, or client failure, and recovers its recorded override after a helper restart. Rapid off/on cycles wait for the previous session to finish cleanup. The version-2 helper fixes intermittent deactivation caused by reading the clock before a concurrently renewed lease timestamp, and publishes status atomically. Lease renewal runs on a dedicated serial queue with App Nap disabled during the session, so a delayed UI loop does not expire the lease. Existing version-1 installations need one administrator approval for the helper upgrade; later toggles do not prompt. The change also replaces the intermittent idle-sleep assertion with a continuous assertion and adds Arabic and English strings, build/uninstall scripts, and implementation documentation.

Distribution and compatibility

This implementation is a direct-distribution fork: it disables App Sandbox and upstream Sparkle updates, and its build script uses a separate bundle identifier. The Xcode project is unchanged. It uses private Apple brightness and lock interfaces, targets macOS 14.6+, and the supplied build script produces an ad-hoc-signed universal app, not a notarized release. These distribution choices will need maintainer review before inclusion in upstream releases.

The helper authorizes the installing user rather than a specific app signature, supports one installing account, and uses a global power setting. Existing external sleep overrides are treated as conflicts. The black cover and lock confirmation reduce the reopening exposure, but hardware and OS timing still require physical validation; this is not a universal zero-frame privacy guarantee. See docs/PROTECTED-LID.md for recovery, removal, and limitations.

Validation

• Universal Release build for Apple Silicon and Intel succeeded; ad-hoc signature verification passed.
• All 19 watchdog/client tests passed (18 together, followed by the added future-timestamp rejection test). Coverage includes a reproduced clock/renewal race, blocking the Swift main actor for 13 seconds while the lease stays active, rapid off/on cycles, cancelled startup, expired leases, and client/helper crashes. Power operations are mocked in these tests.
• Lid transition and lock-reveal timing tests passed, including unknown lock state, interrupted confirmation, and reclosure.
• The real view model passed power-pause tests with inert hardware adapters: quiet low-battery activation and threshold crossing, charger resume below 10%, unknown/fluctuating battery readings, separate thermal reasons, wake handling, privacy-retaining suspension, manual cancellation, expired timers, and queued-start races. No real battery drain or overheating was induced.
• SwiftFormat lint, localization property-list validation, and whitespace checks passed.
• Prior manual testing on one Mac confirmed the lid behavior and reopening privacy fix. The heartbeat and power-pause corrections passed their regression tests and universal builds; extended physical use of this revision and other hardware/OS versions remain unverified.