feat: refactor App component and enhance Canvas collaboration features

[Shreyanshi210205]

Description

This update refactors the Canvas component to introduce a local-first workflow and on-demand collaboration mode.
Previously, users were prompted to join a room on page load ,now this prompt has been removed, and collaboration is now opted via a button.

• Key Changes

1. Default Local Mode
   -The app now starts in a fully local mode where users can draw immediately without connecting to the server.
   -No WebSocket events are emitted in this mode.
   2.Removed Initial Room Prompt
   -The “Join Room” modal no longer appears automatically on load.
   3.New “Collaborate” Button

• Added a button in the toolbar to open the room-joining modal manually.
• When clicked, the user can enter a Room ID to start collaborative mode.

4. Dynamic Collaboration Activation
   -Once a user joins a room, socket communication is enabled.
   -All drawing actions are then synchronized in real-time via WebSockets.

Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

Issues

#26

Checklist

• I have read the Contributing Guidelines.