Add optional lock-aware jiggling pause/resume behavior

[Copilot]

Mouse Jiggler currently prevents sleep even after Win+L, which conflicts with users who want normal lock-screen power behavior. This change adds an opt-in setting to respect Windows session lock state by pausing jiggling while locked.

• Behavior change: lock-aware pause/resume

  • Added Windows session event handling (SystemEvents.SessionSwitch) in MainForm.
  • When Respect lock state is enabled:
    • On SessionLock: jiggling is disabled if currently active.
    • On SessionUnlock: jiggling resumes only if it was auto-paused by the lock event.
  • Uses UI-thread marshaling for session callbacks and unsubscribes on form closing.

• Settings + persistence

  • Added new user-scoped setting: RespectLockedState (default False).
  • Wired setting through:
    • Properties/Settings.settings
    • Properties/Settings.Designer.cs
    • App.config
  • Added MainForm.RespectLockedState property to synchronize UI and persisted settings.

• UI update

  • Added new checkbox under Settings:
    • Respect lock state?
  • Connected checkbox change handler to persist and apply the setting.

• Documentation touch-up

  • Updated README and project description text to mention optional lock-state pause behavior.

if (e.Reason == SessionSwitchReason.SessionLock && this.cbJiggling.Checked)
{
  this._resumeJigglingAfterUnlock = true;
  this.cbJiggling.Checked = false;
}
else if (e.Reason == SessionSwitchReason.SessionUnlock && this._resumeJigglingAfterUnlock)
{
  this._resumeJigglingAfterUnlock = false;
  this.cbJiggling.Checked = true;
}