feat(server): Build Dual-pool WebSocket Manager (Sub-task 3.2)

[archittmittal]

Description

Implement double-pool client subscriptions routing WebSocket messages.
Part of parent issue: #3

Tasks

• Build packages/server/ws_manager.py separating SDK telemetry publishers from UI web subscribers.
• Validate incoming events against Pydantic schemas.
• Write events to the database and broadcast them in real-time.

Acceptance Criteria

• Incoming telemetry does not route back to publishers.
• Events successfully multiplexed to all active UI web subscribers.