fix: Implement complete collaboration feature with database models an…

[Haseeb-1698]

…d API

COLLABORATION FEATURE FIXES:

1. Database Layer

   • Created migration 010_create_collaboration_tables.ts
   • Tables: collaboration_sessions, collaboration_participants
   • Indexes for performance on session_id, user_id, status, is_active
   • Foreign keys to users and labs with CASCADE delete
   • Session status ENUM: active, ended, scheduled
   • Participant role ENUM: host, participant, viewer
   • Screen sharing fields for WebRTC support

2. Data Models (NEW)

   • CollaborationSession model with full validation
   • CollaborationParticipant model with tracking
   • Associations: belongsTo User (host), belongsTo Lab, hasMany Participants
   • TypeScript interfaces and creation types exported
   • Registered models in index.ts

3. Controller Implementation (NEW - 550+ lines)

   • CollaborationController with 6 endpoints: * getSessions(): Get user sessions with filters * getActiveSessions(): Browse active public sessions * getSession(): Get specific session with access control * createSession(): Create session with host auto-join * joinSession(): Join with capacity and status validation * leaveSession(): Leave with auto-end on host exit * endSession(): Host-only session termination
   • Full error handling and logging
   • Role-based access control (host, participant, admin)
   • Participant capacity limits (2-50 users)
   • Auto-cleanup when session empties

4. Routes Update

   • Replaced ALL stub implementations (were returning 501 errors)
   • Added Joi validation schemas for session creation
   • GET /api/collaboration/sessions (user sessions)
   • GET /api/collaboration/sessions/active (public browse)
   • GET /api/collaboration/sessions/:sessionId (single session)
   • POST /api/collaboration/create (with validation)
   • POST /api/collaboration/:sessionId/join
   • POST /api/collaboration/:sessionId/leave
   • DELETE /api/collaboration/:sessionId (end session)

5. Database Configuration

   • Added CollaborationSession and CollaborationParticipant to Sequelize models array
   • Tables will auto-create on server start (development mode)
   • Full model associations initialized

WEBSOCKET INTEGRATION:

• Backend WebSocket already has full collaboration support
• Frontend can now create sessions via REST API and use WebSocket for real-time features

WHAT WAS BROKEN:

• All collaboration REST endpoints returned 501 not yet implemented
• No database tables or models existed
• Frontend could not create, join, or manage sessions

WHAT NOW WORKS:

• Full CRUD operations for collaboration sessions
• Database persistence with proper relationships
• User sessions with host/participant roles
• Public session browsing
• Capacity management and access control
• Auto-cleanup on disconnect

FILES CREATED:

• backend/src/database/migrations/010_create_collaboration_tables.ts
• backend/src/models/CollaborationSession.ts
• backend/src/models/CollaborationParticipant.ts
• backend/src/controllers/CollaborationController.ts

FILES MODIFIED:

• backend/src/routes/collaboration.routes.ts (complete rewrite)
• backend/src/models/index.ts (added exports)
• backend/src/config/database.ts (added models to Sequelize)