Security Indicators & Client Selection (v4)

Summary:
This update focuses on security visibility and improved workflow integration by allowing users to choose their preferred Matrix client.

Key Changes:

• Security Indicators: Added a lock icon to encrypted (E2EE) rooms for quick security verification at a glance.
• Preferred Client Support: You can now explicitly select between Element and Fractal in the settings. The extension will automatically use the selected client to open rooms.
• Protocol Handling: Improved URI dispatching to ensure seamless hand-off between the shell and your desktop Matrix application.
• UI Refinement: Minor layout adjustments in the room list for better readability.