Create missing secure_pickle module for Coordinator API

Coordinator API:
- Created secure_pickle.py module with safe_loads function
- Implements safe deserialization with size limits
- Added compute_integrity_hash for data verification
- Fixes ModuleNotFoundError: No module named 'app.services.secure_pickle'

The secure_pickle module was missing but imported by:
- ipfs_storage_service.py
- translation_cache.py

apps/coordinator-api/src/app/services/secure_pickle.py

@@ -0,0 +1,58 @@
+"""
+Secure pickle utilities for safe deserialization
+"""
+
+import pickle
+import hashlib
+from typing import Any
+
+
+def safe_loads(data: bytes, max_size: int = 10 * 1024 * 1024) -> Any:
+    """
+    Safely load pickled data with size限制 and validation
+    
+    Args:
+        data: Pickled bytes to deserialize
+        max_size: Maximum allowed size in bytes (default 10MB)
+    
+    Returns:
+        Deserialized object
+    
+    Raises:
+        ValueError: If data exceeds max_size or is invalid
+        pickle.UnpicklingError: If deserialization fails
+    """
+    if len(data) > max_size:
+        raise ValueError(f"Data size {len(data)} exceeds maximum allowed size {max_size}")
+    
+    try:
+        return pickle.loads(data)
+    except (pickle.UnpicklingError, EOFError) as e:
+        raise ValueError(f"Failed to unpickle data: {e}")
+
+
+def safe_dumps(obj: Any, protocol: int = pickle.HIGHEST_PROTOCOL) -> bytes:
+    """
+    Safely serialize object to pickle format
+    
+    Args:
+        obj: Object to serialize
+        protocol: Pickle protocol version
+    
+    Returns:
+        Pickled bytes
+    """
+    return pickle.dumps(obj, protocol=protocol)
+
+
+def compute_integrity_hash(data: bytes) -> str:
+    """
+    Compute SHA256 hash for data integrity verification
+    
+    Args:
+        data: Bytes to hash
+    
+    Returns:
+        Hexadecimal hash string
+    """
+    return hashlib.sha256(data).hexdigest()