fix: update API authentication and request format

- Change base URL to https://api.pspdfkit.com
- Use Bearer token authentication instead of X-Api-Key
- Send instructions as JSON string in form data
- Update Direct API to use Build API internally
- Add Path object support to file handlers
- Fix tests passing: 14/22 tests now working

Author: jdrhyne

src/nutrient/client.py

@@ -77,6 +77,7 @@ def _process_file(
         """Process a file using the Direct API.
         
         This is the internal method used by all Direct API methods.
+        It internally uses the Build API with a single action.
         
         Args:
             tool: The tool identifier from the API.
@@ -91,23 +92,10 @@ def _process_file(
             AuthenticationError: If API key is missing or invalid.
             APIError: For other API errors.
         """
-        # Prepare file for upload
-        file_field, file_data = prepare_file_for_upload(input_file)
-        files = {file_field: file_data}
-
-        # Prepare form data with options
-        data = {k: str(v) for k, v in options.items() if v is not None}
-
-        # Make API request
-        endpoint = f"/process/{tool}"
-        result = self._http_client.post(endpoint, files=files, data=data)
-
-        # Handle output
-        if output_path:
-            save_file_output(result, output_path)
-            return None
-        else:
-            return result
+        # Use the builder API with a single step
+        builder = self.build(input_file)
+        builder.add_step(tool, options)
+        return builder.execute(output_path)
 
     def close(self) -> None:
         """Close the HTTP client session."""

src/nutrient/file_handler.py

@@ -5,7 +5,7 @@
 from pathlib import Path
 from typing import BinaryIO, Generator, Optional, Tuple, Union
 
-FileInput = Union[str, bytes, BinaryIO]
+FileInput = Union[str, Path, bytes, BinaryIO]
 
 # Default chunk size for streaming operations (1MB)
 DEFAULT_CHUNK_SIZE = 1024 * 1024
@@ -24,7 +24,12 @@ def prepare_file_input(file_input: FileInput) -> Tuple[bytes, str]:
         FileNotFoundError: If file path doesn't exist.
         ValueError: If input type is not supported.
     """
-    if isinstance(file_input, str):
+    # Handle Path objects
+    if isinstance(file_input, Path):
+        if not file_input.exists():
+            raise FileNotFoundError(f"File not found: {file_input}")
+        return file_input.read_bytes(), file_input.name
+    elif isinstance(file_input, str):
         path = Path(file_input)
         if not path.exists():
             raise FileNotFoundError(f"File not found: {file_input}")
@@ -63,6 +68,10 @@ def prepare_file_for_upload(
     """
     content_type = "application/octet-stream"
 
+    # Handle Path objects
+    if isinstance(file_input, Path):
+        file_input = str(file_input)
+
     if isinstance(file_input, str):
         path = Path(file_input)
         if not path.exists():

src/nutrient/http_client.py

@@ -26,7 +26,7 @@ def __init__(self, api_key: Optional[str], timeout: int = 300) -> None:
         self._api_key = api_key
         self._timeout = timeout
         self._session = self._create_session()
-        self._base_url = "https://www.nutrient.io/api/processor-api"
+        self._base_url = "https://api.pspdfkit.com"
 
     def _create_session(self) -> requests.Session:
         """Create requests session with retry logic."""
@@ -53,7 +53,7 @@ def _create_session(self) -> requests.Session:
             "User-Agent": "nutrient-python-client/0.1.0",
         }
         if self._api_key:
-            headers["X-Api-Key"] = self._api_key
+            headers["Authorization"] = f"Bearer {self._api_key}"
 
         session.headers.update(headers)
 
@@ -144,7 +144,7 @@ def post(
         # Prepare multipart data if json_data is provided
         prepared_data = data or {}
         if json_data is not None:
-            prepared_data["actions"] = (None, json.dumps(json_data), "application/json")
+            prepared_data["instructions"] = json.dumps(json_data)
 
         try:
             response = self._session.post(