Add admin panel, WebSocket support, and API versioning

Introduce an admin portal (React + Nginx), WebSocket routing, and
API versioning middleware with `/api/v1/` prefix deprecation.
Add master API key authentication, new Prometheus metrics for AI
token consumption and active WebSockets, and extend S3 config
with a public endpoint URL. Update test paths and fixtures to
align with the new routing structure.

tests/test_exif_extended.py

@@ -8,10 +8,16 @@ def test_dms_to_decimal():
     assert _dms_to_decimal(dms, "N") == 48.8566167
     assert _dms_to_decimal(dms, "S") == -48.8566167
 
+@pytest.mark.asyncio
 @patch("app.services.exif_service.piexif")
 @patch("app.services.exif_service.PILImage")
 @patch("app.services.exif_service.Path.exists", return_value=True)
-def test_extract_exif_success(mock_path_exists, mock_pil, mock_piexif):
+@patch("app.services.exif_service.get_storage_backend")
+async def test_extract_exif_success(mock_get_storage_backend, mock_path_exists, mock_pil, mock_piexif):
+    from unittest.mock import AsyncMock
+    mock_backend = MagicMock()
+    mock_backend.get_bytes = AsyncMock(return_value=b"fake")
+    mock_get_storage_backend.return_value = mock_backend
     # Mock piexif data
     import piexif
     mock_data = {
@@ -45,7 +51,7 @@ def test_extract_exif_success(mock_path_exists, mock_pil, mock_piexif):
     mock_img = mock_pil.open.return_value.__enter__.return_value
     mock_img._getexif.return_value = {271: "Canon"} # 271 is Make
     
-    result = extract_exif("fake/path.jpg")
+    result = await extract_exif("fake/path.jpg")
     
     assert result["make"] == "Canon"
     assert result["model"] == "EOS R5"