feat: Implement Smart Session Guard for Lock and Sleep Awareness

[0xarchit]

🐾 Pull Request Description

Summary
This PR introduces the "Smart Session Guard," making PauseCat aware of the Windows session state and system power events. It ensures the work timer only ticks when the user is
actually at their desk and prevents reminders from triggering on locked screens.

Related Issues
Fixes #37

🚀 Key Changes

• Native Lock Detection: Integrated Win32 WTSRegisterSessionNotification to pause the timer automatically when the screen is locked (Win+L).
• Power State Awareness: Implemented WM_POWERBROADCAST handling to detect system sleep/suspend and resume events.
• Zero-Ghosting Guard: Added a strict verification layer that prevents overlay initialization if the user session is not active and unlocked.
• Automatic Dismiss: Configured the app to automatically clear active break reminders if the session is locked during a break.
• RAM-Only State: Maintained your preference for non-persistent timers; all session logic lives purely in RAM and resets cleanly upon application restart or system reboot.

🛠 Technical Details

• Added Win32_System_RemoteDesktop to Cargo.toml for session change notifications.
• Refactored the main event loop to route SessionLocked and SessionUnlocked events to the timer engine.
• Bumped application version to v1.0.1.

✅ Verification

• Verified on Windows 11 that locking the screen instantly freezes the work timer.
• Confirmed that the timer resumes seamlessly upon unlocking without losing progress.
• Verified that the break reminder does not trigger while the session is locked.
• Successfully built with MSVC optimizations (cargo build --release).

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