[AZ-178] Implement streaming video detection endpoint

- Added `/detect/video` endpoint for true streaming video detection, allowing inference to start as upload bytes arrive.
- Introduced `run_detect_video_stream` method in the inference module to handle video processing from a file-like object.
- Updated media hashing to include a new function for computing hashes directly from files with minimal I/O.
- Enhanced documentation to reflect changes in video processing and API behavior.

Made-with: Cursor

_docs/02_document/modules/media_hash.md

@@ -9,6 +9,7 @@ Content-based hashing for media files using XxHash64 with a deterministic sampli
 | Function | Signature | Description |
 |----------|-----------|-------------|
 | `compute_media_content_hash` | `(data: bytes, virtual: bool = False) -> str` | Returns hex XxHash64 digest of sampled content. If `virtual=True`, prefixes with "V". |
+| `compute_media_content_hash_from_file` | `(path: str, virtual: bool = False) -> str` | Same algorithm but reads sampling regions directly from a file on disk — only 3 KB I/O regardless of file size. Produces identical hashes to the bytes-based version. (AZ-178) |
 
 ## Internal Logic
 
@@ -27,7 +28,7 @@ The sampling avoids reading the full file through the hash function while still
 
 ## Consumers
 
-- `main` — computes content hash for uploaded media in `POST /detect` to use as the media record ID and storage filename
+- `main` — computes content hash for uploaded media in `POST /detect` (bytes version) and `POST /detect/video` (file version) to use as the media record ID and storage filename
 
 ## Data Models
 
@@ -48,3 +49,4 @@ None. The hash is non-cryptographic (fast, not tamper-resistant).
 ## Tests
 
 - `tests/test_media_hash.py` — covers small files, large files, and virtual prefix behavior
+- `tests/test_az178_streaming_video.py::TestMediaContentHashFromFile` — verifies file-based hash matches bytes-based hash for small, large, boundary, and virtual cases