feat: Initial commit - Task Reporter incident response system

Complete implementation of the production line incident response system (生產線異常即時反應系統) including:

Backend (FastAPI):
- User authentication with AD integration and session management
- Chat room management (create, list, update, members, roles)
- Real-time messaging via WebSocket (typing indicators, reactions)
- File storage with MinIO (upload, download, image preview)

Frontend (React + Vite):
- Authentication flow with token management
- Room list with filtering, search, and pagination
- Real-time chat interface with WebSocket
- File upload with drag-and-drop and image preview
- Member management and room settings
- Breadcrumb navigation
- 53 unit tests (Vitest)

Specifications:
- authentication: AD auth, sessions, JWT tokens
- chat-room: rooms, members, templates
- realtime-messaging: WebSocket, messages, reactions
- file-storage: MinIO integration, file management
- frontend-core: React SPA structure

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/modules/realtime/models.py

@@ -0,0 +1,106 @@
+"""SQLAlchemy models for realtime messaging
+
+Tables:
+- messages: Stores all messages sent in incident rooms
+- message_reactions: User reactions to messages (emoji)
+- message_edit_history: Audit trail for message edits
+"""
+from sqlalchemy import Column, Integer, String, Text, DateTime, Enum, ForeignKey, UniqueConstraint, Index, BigInteger, JSON
+from sqlalchemy.orm import relationship
+from datetime import datetime
+import enum
+import uuid
+from app.core.database import Base
+
+
+class MessageType(str, enum.Enum):
+    """Types of messages in incident rooms"""
+    TEXT = "text"
+    IMAGE_REF = "image_ref"
+    FILE_REF = "file_ref"
+    SYSTEM = "system"
+    INCIDENT_DATA = "incident_data"
+
+
+class Message(Base):
+    """Message model for incident room communications"""
+
+    __tablename__ = "messages"
+
+    message_id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    room_id = Column(String(36), ForeignKey("incident_rooms.room_id", ondelete="CASCADE"), nullable=False)
+    sender_id = Column(String(255), nullable=False)  # User email/ID
+    content = Column(Text, nullable=False)
+    message_type = Column(Enum(MessageType), default=MessageType.TEXT, nullable=False)
+
+    # Message metadata for structured data, mentions, file references, etc.
+    message_metadata = Column(JSON)
+
+    # Timestamps
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+    edited_at = Column(DateTime)  # Last edit timestamp
+    deleted_at = Column(DateTime)  # Soft delete timestamp
+
+    # Sequence number for FIFO ordering within a room
+    # Note: Autoincrement doesn't work for non-PK in SQLite, will be set in service layer
+    sequence_number = Column(BigInteger, nullable=False)
+
+    # Relationships
+    reactions = relationship("MessageReaction", back_populates="message", cascade="all, delete-orphan")
+    edit_history = relationship("MessageEditHistory", back_populates="message", cascade="all, delete-orphan")
+
+    # Indexes for common queries
+    __table_args__ = (
+        Index("ix_messages_room_created", "room_id", "created_at"),
+        Index("ix_messages_room_sequence", "room_id", "sequence_number"),
+        Index("ix_messages_sender", "sender_id"),
+        # PostgreSQL full-text search index on content (commented for SQLite compatibility)
+        # Note: Uncomment when using PostgreSQL with pg_trgm extension enabled
+        # Index("ix_messages_content_search", "content", postgresql_using='gin', postgresql_ops={'content': 'gin_trgm_ops'}),
+    )
+
+
+class MessageReaction(Base):
+    """Message reaction model for emoji reactions"""
+
+    __tablename__ = "message_reactions"
+
+    reaction_id = Column(Integer, primary_key=True, autoincrement=True)
+    message_id = Column(String(36), ForeignKey("messages.message_id", ondelete="CASCADE"), nullable=False)
+    user_id = Column(String(255), nullable=False)  # User email/ID who reacted
+    emoji = Column(String(10), nullable=False)  # Emoji character or code
+
+    # Timestamp
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+
+    # Relationships
+    message = relationship("Message", back_populates="reactions")
+
+    # Constraints and indexes
+    __table_args__ = (
+        # Ensure unique reaction per user per message
+        UniqueConstraint("message_id", "user_id", "emoji", name="uq_message_reaction"),
+        Index("ix_message_reactions_message", "message_id"),
+    )
+
+
+class MessageEditHistory(Base):
+    """Message edit history model for audit trail"""
+
+    __tablename__ = "message_edit_history"
+
+    edit_id = Column(Integer, primary_key=True, autoincrement=True)
+    message_id = Column(String(36), ForeignKey("messages.message_id", ondelete="CASCADE"), nullable=False)
+    original_content = Column(Text, nullable=False)  # Content before edit
+    edited_by = Column(String(255), nullable=False)  # User who made the edit
+
+    # Timestamp
+    edited_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+
+    # Relationships
+    message = relationship("Message", back_populates="edit_history")
+
+    # Indexes
+    __table_args__ = (
+        Index("ix_message_edit_history_message", "message_id", "edited_at"),
+    )