Add `.excalidraw` file for app planning & brainstorming

[louicoder]

Title: Add .excalidraw file for app planning & homescreen design brainstorming

Description:
To improve collaboration and clarify our design direction, we should create and commit an .excalidraw file to the repository. This file will serve as a shared space for:

• Brainstorming app features and layout ideas.
• Planning the homescreen design in detail (UI layout, navigation, key components).
• Mapping user flows and interactions.

Having this visual planning document in version control enables the entire team to update, review, and track the design evolution alongside the codebase.

Acceptance Criteria:

• A new .excalidraw file is created in a /design or /docs directory.

• File contains:

  • Initial homescreen wireframe with key UI elements.
  • Notes and annotations for planned features.
  • Optional: other app flow sketches if relevant.

• Committed to Git so changes can be reviewed via PRs.

• Include brief usage instructions in README for editing/viewing .excalidraw files.

Implementation Details:

1. Use [Excalidraw Web App](https://excalidraw.com/) or the VS Code Excalidraw extension.
2. Save file as app-planning.excalidraw (or similar).
3. Place it under a /design folder at the root of the repo.
4. Commit and push to the master/main branch (or via a PR).

References:

• [Excalidraw Documentation](https://github.com/excalidraw/excalidraw)
• [VS Code Excalidraw Extension](https://marketplace.visualstudio.com/items?itemName=pomdtr.excalidraw-editor)