feat(ws): rewrite websocket flow using Actix actors instead of manual…

[anand9125]

This PR rewrites the entire WebSocket flow to use Actix actors instead of the previous manual handler-based implementation.
The old approach mixed state management, routing, and message broadcasting inside a single handler, which caused issues with lifetimes, shared mutability, and concurrency.

The new architecture fully adopts the Actix actor model:

Changes:
Introduced a WsClient actor to encapsulate per-connection state and handle incoming WebSocket frames.
Added a RoomManager actor responsible for room creation, membership tracking, and broadcasting messages to connected clients.
Replaced manual message routing with typed Actix messages (Join, Leave, RoomMessage, etc.).
Removed lifetime-dependent logic and moved all mutable shared state into Actor mailboxes.
Improved isolation between clients — no shared mutable state, no need for mutexes.
Ensured safe, concurrent communication using Actix’s actor scheduling and message passing.

Benefits:

Cleaner separation of concerns (client vs room management).
No lifetime errors from shared references.
Proper concurrency — actors never block the event loop.
Easier to extend (adding rooms, private messages, game logic, etc.)
More idiomatic Rust + Actix implementation.