feat(auth): add get_current_user_from_api_token dependency

- Validates API tokens (or_api_* prefix)
- SHA-256 hash lookup in api_tokens table
- Updates last_used_at on each request
- Distinguishes from JWT tokens (401 with clear error)

src/openrouter_monitor/dependencies/__init__.py

@@ -1,4 +1,22 @@
 """Dependencies package for OpenRouter Monitor."""
-from openrouter_monitor.dependencies.auth import get_current_user, security
+from openrouter_monitor.dependencies.auth import (
+    get_current_user,
+    get_current_user_from_api_token,
+    security,
+    api_token_security,
+)
+from openrouter_monitor.dependencies.rate_limit import (
+    RateLimiter,
+    rate_limit_dependency,
+    rate_limiter,
+)
 
-__all__ = ["get_current_user", "security"]
+__all__ = [
+    "get_current_user",
+    "get_current_user_from_api_token",
+    "security",
+    "api_token_security",
+    "RateLimiter",
+    "rate_limit_dependency",
+    "rate_limiter",
+]

src/openrouter_monitor/dependencies/auth.py

@@ -1,20 +1,25 @@
 """Authentication dependencies.
 
 T21: get_current_user dependency for protected endpoints.
+T36: get_current_user_from_api_token dependency for public API endpoints.
 """
+import hashlib
+from datetime import datetime
+
 from fastapi import Depends, HTTPException, status
 from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
 from jose import JWTError
 from sqlalchemy.orm import Session
 
 from openrouter_monitor.database import get_db
-from openrouter_monitor.models import User
+from openrouter_monitor.models import User, ApiToken
 from openrouter_monitor.schemas import TokenData
 from openrouter_monitor.services import decode_access_token
 
 
-# HTTP Bearer security scheme
+# HTTP Bearer security schemes
 security = HTTPBearer()
+api_token_security = HTTPBearer(auto_error=False)
 
 
 async def get_current_user(
@@ -77,3 +82,74 @@ async def get_current_user(
         )
     
     return user
+
+
+async def get_current_user_from_api_token(
+    credentials: HTTPAuthorizationCredentials = Depends(api_token_security),
+    db: Session = Depends(get_db)
+) -> User:
+    """Get current authenticated user from API token (for public API endpoints).
+    
+    This dependency extracts the API token from the Authorization header,
+    verifies it against the database, updates last_used_at, and returns
+    the corresponding user.
+    
+    API tokens start with 'or_api_' prefix and are different from JWT tokens.
+    
+    Args:
+        credentials: HTTP Authorization credentials containing the Bearer token
+        db: Database session
+        
+    Returns:
+        The authenticated User object
+        
+    Raises:
+        HTTPException: 401 if token is invalid, inactive, or user not found/inactive
+    """
+    credentials_exception = HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Invalid API token",
+        headers={"WWW-Authenticate": "Bearer"},
+    )
+    
+    # Check if credentials were provided
+    if credentials is None:
+        raise credentials_exception
+    
+    token = credentials.credentials
+    
+    # Check if token looks like an API token (starts with 'or_api_')
+    # JWT tokens don't have this prefix
+    if not token.startswith("or_api_"):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Invalid token type. Use API token, not JWT.",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    # Hash the token with SHA-256 for lookup
+    token_hash = hashlib.sha256(token.encode()).hexdigest()
+    
+    # Look up the token in the database
+    api_token = db.query(ApiToken).filter(
+        ApiToken.token_hash == token_hash,
+        ApiToken.is_active == True
+    ).first()
+    
+    if not api_token:
+        raise credentials_exception
+    
+    # Update last_used_at timestamp
+    api_token.last_used_at = datetime.utcnow()
+    db.commit()
+    
+    # Get the user associated with this token
+    user = db.query(User).filter(
+        User.id == api_token.user_id,
+        User.is_active == True
+    ).first()
+    
+    if not user:
+        raise credentials_exception
+    
+    return user