Add launchd-based system scheduling and UI support for system-scheduled timers

[holgerkrupp]

Motivation

• Allow repeating timers to run even when the app is not in the foreground by installing per-user LaunchAgent jobs so macOS launchd handles recurring launches.
• Surface and reconcile the system-scheduled state in the model and UI so scheduled timers show accurate next-fire times and progress.
• Fall back to the in-app Timer when launchd installation fails and support correct countdown visuals for system-scheduled timers.

Description

• Add LaunchAgentScheduler utility with install, uninstall, isInstalled, label, and helper methods that write a plist into ~/Library/LaunchAgents and call launchctl to bootstrap/enable jobs.
• Extend TimerItem with isSystemScheduleEnabled and systemScheduleStartDate, integrate LaunchAgentScheduler in startTimer/stopTimer, add reconcileSystemScheduleState, nextSystemFireDate, and update calcProgress to compute progress for system-scheduled timers without an in-app Timer.
• Update views: call timer.reconcileSystemScheduleState() from TimerItemList, show a "Scheduled by macOS launchd" caption and pass repeats into CountdownView in TimerSummaryView, and add a clock ticker to advance nextFireDate for system-scheduled timers; change CountdownView to accept repeats and compute wrap-around remaining time via remainingTime(until:from:).
• Add a short scheduling note to README.md describing the launchd behavior and when the app falls back to in-app timers.

Testing

• No automated tests were executed for this change.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Use a real per-user LaunchAgents location

With AutoRun.entitlements enabling the App Sandbox, FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask) resolves inside the app container rather than the user's ~/Library. That means these plists are written under the container's Library/LaunchAgents, so after a logout/reboot launchd will not auto-load them from the standard per-user LaunchAgents directory, while reconcileSystemScheduleState() can still mark the timer active just because the container plist exists; users then see an active system-scheduled timer that never fires.

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[chatgpt-codex-connector]

Clear stale in-app timers after launchd install

When a timer previously used the in-app path (for example a one-shot timer or a launchd fallback), stopTimer() only invalidates the Timer and leaves the non-nil object in timer. This success path returns without clearing it, but isSystemScheduled requires timer == nil, so the UI will not show the launchd state and the clock handler will not advance nextFireDate even though the LaunchAgent was installed.

Useful? React with 👍 / 👎.