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/dotenv/ipython.py

@@ -0,0 +1,50 @@
+from IPython.core.magic import Magics, line_magic, magics_class  # type: ignore
+from IPython.core.magic_arguments import (
+    argument,
+    magic_arguments,
+    parse_argstring,
+)  # type: ignore
+
+from .main import find_dotenv, load_dotenv
+
+
+@magics_class
+class IPythonDotEnv(Magics):
+    @magic_arguments()
+    @argument(
+        "-o",
+        "--override",
+        action="store_true",
+        help="Indicate to override existing variables",
+    )
+    @argument(
+        "-v",
+        "--verbose",
+        action="store_true",
+        help="Indicate function calls to be verbose",
+    )
+    @argument(
+        "dotenv_path",
+        nargs="?",
+        type=str,
+        default=".env",
+        help="Search in increasingly higher folders for the `dotenv_path`",
+    )
+    @line_magic
+    def dotenv(self, line):
+        args = parse_argstring(self.dotenv, line)
+        # Locate the .env file
+        dotenv_path = args.dotenv_path
+        try:
+            dotenv_path = find_dotenv(dotenv_path, True, True)
+        except IOError:
+            print("cannot find .env file")
+            return
+
+        # Load the .env file
+        load_dotenv(dotenv_path, verbose=args.verbose, override=args.override)
+
+
+def load_ipython_extension(ipython):
+    """Register the %dotenv magic."""
+    ipython.register_magics(IPythonDotEnv)