feat(phase1): add image storage utilities

- Create backend/services/image_storage.py with 4 core functions:
  - sanitize_filename(): remove unsafe chars, limit to 255 chars, convert to lowercase
  - get_unique_filename(): handle collisions with UUID suffix (format: {name}_{uuid8}_{variant}.jpg)
  - ensure_image_directories(): create /images/ root and category subdirs on startup
  - save_image(): save bytes to /images/{category}/{filename}, returns relative path
- Create comprehensive test suite (22 tests) covering all functionality
- Integrate ensure_image_directories() into FastAPI startup event
- Directory structure: /images/{category}/{filename}
- Collision handling: auto-suffix with UUID if filename exists
- All tests passing, pathlib.Path for safe operations

venv/lib/python3.12/site-packages/anthropic/_resource.py

@@ -0,0 +1,41 @@
+# File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
+
+from __future__ import annotations
+
+import time
+
+import anyio
+
+from ._base_client import SyncAPIClient, AsyncAPIClient
+
+
+class SyncAPIResource:
+    _client: SyncAPIClient
+
+    def __init__(self, client: SyncAPIClient) -> None:
+        self._client = client
+        self._get = client.get
+        self._post = client.post
+        self._patch = client.patch
+        self._put = client.put
+        self._delete = client.delete
+        self._get_api_list = client.get_api_list
+
+    def _sleep(self, seconds: float) -> None:
+        time.sleep(seconds)
+
+
+class AsyncAPIResource:
+    _client: AsyncAPIClient
+
+    def __init__(self, client: AsyncAPIClient) -> None:
+        self._client = client
+        self._get = client.get
+        self._post = client.post
+        self._patch = client.patch
+        self._put = client.put
+        self._delete = client.delete
+        self._get_api_list = client.get_api_list
+
+    async def _sleep(self, seconds: float) -> None:
+        await anyio.sleep(seconds)