Fix add_file to accept both Path and string

ipfs_client.py

@@ -45,18 +45,22 @@ def _multiaddr_to_url(multiaddr: str) -> str:
 IPFS_BASE_URL = _multiaddr_to_url(IPFS_API)
 
 
-def add_file(file_path: Path, pin: bool = True) -> Optional[str]:
+def add_file(file_path: Union[Path, str], pin: bool = True) -> Optional[str]:
     """
     Add a file to IPFS and optionally pin it.
 
     Args:
-        file_path: Path to the file to add
+        file_path: Path to the file to add (Path object or string)
         pin: Whether to pin the file (default: True)
 
     Returns:
         IPFS CID (content identifier) or None on failure
     """
     try:
+        # Ensure file_path is a Path object
+        if isinstance(file_path, str):
+            file_path = Path(file_path)
+
         url = f"{IPFS_BASE_URL}/api/v0/add"
         params = {"pin": str(pin).lower()}