Register uploaded images in asset database when --enable-assets is set

Add register_file_in_place() service function to ingest module for
registering already-saved files without moving them. Call it from the
/upload/image endpoint to return asset metadata in the response.

Amp-Thread-ID: https://ampcode.com/threads/T-019ce023-3384-7560-bacf-de40b0de0dd2
Co-authored-by: Amp <amp@ampcode.com>

app/assets/services/ingest.py

@@ -346,6 +346,61 @@ def upload_from_temp_path(
     )
 
 
+def register_file_in_place(
+    abs_path: str,
+    name: str,
+    tags: list[str],
+    owner_id: str = "",
+    mime_type: str | None = None,
+) -> UploadResult:
+    """Register an already-saved file in the asset database without moving it."""
+    try:
+        digest, _ = hashing.compute_blake3_hash(abs_path)
+    except ImportError as e:
+        raise DependencyMissingError(str(e))
+    except Exception as e:
+        raise RuntimeError(f"failed to hash file: {e}")
+    asset_hash = "blake3:" + digest
+
+    size_bytes, mtime_ns = get_size_and_mtime_ns(abs_path)
+    content_type = mime_type or (
+        mimetypes.guess_type(abs_path, strict=False)[0]
+        or "application/octet-stream"
+    )
+
+    ingest_result = _ingest_file_from_path(
+        abs_path=abs_path,
+        asset_hash=asset_hash,
+        size_bytes=size_bytes,
+        mtime_ns=mtime_ns,
+        mime_type=content_type,
+        info_name=_sanitize_filename(name, fallback=digest),
+        owner_id=owner_id,
+        tags=tags,
+        tag_origin="upload",
+        require_existing_tags=False,
+    )
+    reference_id = ingest_result.reference_id
+    if not reference_id:
+        raise RuntimeError("failed to create asset reference")
+
+    with create_session() as session:
+        pair = fetch_reference_and_asset(
+            session, reference_id=reference_id, owner_id=owner_id
+        )
+        if not pair:
+            raise RuntimeError("inconsistent DB state after ingest")
+        ref, asset = pair
+        tag_names = get_reference_tags(session, reference_id=ref.id)
+
+    return UploadResult(
+        ref=extract_reference_data(ref),
+        asset=extract_asset_data(asset),
+        tags=tag_names,
+        created_new=ingest_result.asset_created,
+    )
+
+
 def create_from_hash(
     hash_str: str,
     name: str,