Add deployment Docker Compose file, testing utilities, security helpers, and database initialization script

- Introduced `docker-compose.deploy.yml` for deployment scenarios with pre-built Docker images.
- Added `auth_test_utils.py` to simplify authentication testing in FastAPI.
- Implemented `security.py` for token-based operations like file uploads and password resets.
- Created `init_db.py` for database initialization and superuser creation during startup.
- Updated dependencies and tests to support optional authentication in FastAPI.
- Enhanced entrypoint script to handle database initialization.

backend/app/utils/security.py

@@ -0,0 +1,110 @@
+"""
+Security utilities for token-based operations.
+
+This module provides utilities for creating and verifying signed tokens,
+useful for operations like file uploads, password resets, or any other
+time-limited, single-use operations.
+"""
+import base64
+import hashlib
+import json
+import secrets
+import time
+from typing import Dict, Any, Optional
+
+from app.core.config import settings
+
+
+def create_upload_token(file_path: str, content_type: str, expires_in: int = 300) -> str:
+    """
+    Create a signed token for secure file uploads.
+
+    This generates a time-limited, single-use token that can be verified
+    to ensure the upload is authorized.
+
+    Args:
+        file_path: The destination path for the file
+        content_type: The expected content type (e.g., "image/jpeg")
+        expires_in: Expiration time in seconds (default: 300 = 5 minutes)
+
+    Returns:
+        A base64 encoded token string
+
+    Example:
+        >>> token = create_upload_token("/uploads/avatar.jpg", "image/jpeg")
+        >>> # Send token to client, client includes it in upload request
+    """
+    # Create the payload
+    payload = {
+        "path": file_path,
+        "content_type": content_type,
+        "exp": int(time.time()) + expires_in,
+        "nonce": secrets.token_hex(8)  # Add randomness to prevent token reuse
+    }
+
+    # Convert to JSON and encode
+    payload_bytes = json.dumps(payload).encode('utf-8')
+
+    # Create a signature using the secret key
+    signature = hashlib.sha256(
+        payload_bytes + settings.SECRET_KEY.encode('utf-8')
+    ).hexdigest()
+
+    # Combine payload and signature
+    token_data = {
+        "payload": payload,
+        "signature": signature
+    }
+
+    # Encode the final token
+    token_json = json.dumps(token_data)
+    token = base64.urlsafe_b64encode(token_json.encode('utf-8')).decode('utf-8')
+
+    return token
+
+
+def verify_upload_token(token: str) -> Optional[Dict[str, Any]]:
+    """
+    Verify an upload token and return the payload if valid.
+
+    Args:
+        token: The token string to verify
+
+    Returns:
+        The payload dictionary if valid, None if invalid or expired
+
+    Example:
+        >>> payload = verify_upload_token(token_from_client)
+        >>> if payload:
+        ...     file_path = payload["path"]
+        ...     content_type = payload["content_type"]
+        ...     # Proceed with upload
+        ... else:
+        ...     # Token invalid or expired
+    """
+    try:
+        # Decode the token
+        token_json = base64.urlsafe_b64decode(token.encode('utf-8')).decode('utf-8')
+        token_data = json.loads(token_json)
+
+        # Extract payload and signature
+        payload = token_data["payload"]
+        signature = token_data["signature"]
+
+        # Verify signature
+        payload_bytes = json.dumps(payload).encode('utf-8')
+        expected_signature = hashlib.sha256(
+            payload_bytes + settings.SECRET_KEY.encode('utf-8')
+        ).hexdigest()
+
+        if signature != expected_signature:
+            return None
+
+        # Check expiration
+        if payload["exp"] < int(time.time()):
+            return None
+
+        return payload
+
+    except (ValueError, KeyError, json.JSONDecodeError):
+        return None