Create and Add an app icon

Description: We need to create and add the app icon (#60) for the Aossie Open Peer Chat app. The app icon should reflect the core features of the app—secure, open, and user-friendly communication. It should incorporate elements like a chat bubble, lock symbol, or encryption theme to emphasize the privacy and peer-to-peer nature of the platform.

Requirements:
Design a sleek and minimalistic app icon.
Use shades of blue and green to represent trust and communication.
Consider adding a subtle lock or encryption symbol to highlight security.
Keep the icon simple, recognizable, and easy to scale for different device resolutions.
The icon should be in the standard formats (e.g., PNG, SVG) and appropriately sized for various use cases (e.g., app stores, notifications).

Expected Outcome: The icon should be added to the app repository and integrated into the app's codebase for use across platforms.