feat: Add database migrations and auth system

- Add Alembic for database migrations
- Implement user authentication system
- Update frontend styles and components
- Add new test audio functionality
- Update stream management and UI

auth.py

@@ -0,0 +1,73 @@
+"""Authentication middleware and utilities for dicta2stream"""
+from fastapi import Request, HTTPException, Depends, status
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
+from sqlmodel import Session
+from typing import Optional
+
+from models import User, Session as DBSession, verify_session
+from database import get_db
+
+security = HTTPBearer()
+
+def get_current_user(
+    request: Request,
+    db: Session = Depends(get_db),
+    credentials: HTTPAuthorizationCredentials = Depends(security)
+) -> User:
+    """Dependency to get the current authenticated user"""
+    token = credentials.credentials
+    db_session = verify_session(db, token)
+    
+    if not db_session:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Invalid or expired session",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    # Get the user from the session
+    user = db.exec(
+        select(User).where(User.username == db_session.user_id)
+    ).first()
+    
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="User not found",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    # Attach the session to the request state for later use
+    request.state.session = db_session
+    return user
+
+
+def get_optional_user(
+    request: Request,
+    db: Session = Depends(get_db),
+    credentials: Optional[HTTPAuthorizationCredentials] = Depends(security, use_cache=False)
+) -> Optional[User]:
+    """Dependency that returns the current user if authenticated, None otherwise"""
+    if not credentials:
+        return None
+        
+    try:
+        return get_current_user(request, db, credentials)
+    except HTTPException:
+        return None
+
+
+def create_session(db: Session, user: User, request: Request) -> DBSession:
+    """Create a new session for the user"""
+    user_agent = request.headers.get("user-agent")
+    ip_address = request.client.host if request.client else "0.0.0.0"
+    
+    session = DBSession.create_for_user(
+        user_id=user.username,
+        ip_address=ip_address,
+        user_agent=user_agent
+    )
+    
+    db.add(session)
+    db.commit()
+    return session