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/_decoders/jsonl.py

@@ -0,0 +1,123 @@
+from __future__ import annotations
+
+import json
+from typing_extensions import Generic, TypeVar, Iterator, AsyncIterator
+
+import httpx
+
+from .._models import construct_type_unchecked
+
+_T = TypeVar("_T")
+
+
+class JSONLDecoder(Generic[_T]):
+    """A decoder for [JSON Lines](https://jsonlines.org) format.
+
+    This class provides an iterator over a byte-iterator that parses each JSON Line
+    into a given type.
+    """
+
+    http_response: httpx.Response
+    """The HTTP response this decoder was constructed from"""
+
+    def __init__(
+        self,
+        *,
+        raw_iterator: Iterator[bytes],
+        line_type: type[_T],
+        http_response: httpx.Response,
+    ) -> None:
+        super().__init__()
+        self.http_response = http_response
+        self._raw_iterator = raw_iterator
+        self._line_type = line_type
+        self._iterator = self.__decode__()
+
+    def close(self) -> None:
+        """Close the response body stream.
+
+        This is called automatically if you consume the entire stream.
+        """
+        self.http_response.close()
+
+    def __decode__(self) -> Iterator[_T]:
+        buf = b""
+        for chunk in self._raw_iterator:
+            for line in chunk.splitlines(keepends=True):
+                buf += line
+                if buf.endswith((b"\r", b"\n", b"\r\n")):
+                    yield construct_type_unchecked(
+                        value=json.loads(buf),
+                        type_=self._line_type,
+                    )
+                    buf = b""
+
+        # flush
+        if buf:
+            yield construct_type_unchecked(
+                value=json.loads(buf),
+                type_=self._line_type,
+            )
+
+    def __next__(self) -> _T:
+        return self._iterator.__next__()
+
+    def __iter__(self) -> Iterator[_T]:
+        for item in self._iterator:
+            yield item
+
+
+class AsyncJSONLDecoder(Generic[_T]):
+    """A decoder for [JSON Lines](https://jsonlines.org) format.
+
+    This class provides an async iterator over a byte-iterator that parses each JSON Line
+    into a given type.
+    """
+
+    http_response: httpx.Response
+
+    def __init__(
+        self,
+        *,
+        raw_iterator: AsyncIterator[bytes],
+        line_type: type[_T],
+        http_response: httpx.Response,
+    ) -> None:
+        super().__init__()
+        self.http_response = http_response
+        self._raw_iterator = raw_iterator
+        self._line_type = line_type
+        self._iterator = self.__decode__()
+
+    async def close(self) -> None:
+        """Close the response body stream.
+
+        This is called automatically if you consume the entire stream.
+        """
+        await self.http_response.aclose()
+
+    async def __decode__(self) -> AsyncIterator[_T]:
+        buf = b""
+        async for chunk in self._raw_iterator:
+            for line in chunk.splitlines(keepends=True):
+                buf += line
+                if buf.endswith((b"\r", b"\n", b"\r\n")):
+                    yield construct_type_unchecked(
+                        value=json.loads(buf),
+                        type_=self._line_type,
+                    )
+                    buf = b""
+
+        # flush
+        if buf:
+            yield construct_type_unchecked(
+                value=json.loads(buf),
+                type_=self._line_type,
+            )
+
+    async def __anext__(self) -> _T:
+        return await self._iterator.__anext__()
+
+    async def __aiter__(self) -> AsyncIterator[_T]:
+        async for item in self._iterator:
+            yield item