Add media browser with grid/compact/list views and single-click playback

- Add browser UI with three view modes (grid, compact, list) and pagination
- Add file browsing, thumbnail loading, download, and play endpoints
- Add duration extraction via mutagen for media files
- Single-click plays media or navigates folders, with play overlay on hover
- Add type badges, file size display, and duration metadata
- Add localization keys for browser UI (en/ru)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

media_server/routes/browser.py

@@ -7,10 +7,10 @@ from typing import Optional
 from urllib.parse import unquote
 
 from fastapi import APIRouter, Depends, HTTPException, Query, Response
-from fastapi.responses import StreamingResponse
+from fastapi.responses import FileResponse, StreamingResponse
 from pydantic import BaseModel, Field
 
-from ..auth import verify_token
+from ..auth import verify_token, verify_token_or_query
 from ..config import MediaFolderConfig, settings
 from ..config_manager import config_manager
 from ..services.browser_service import BrowserService
@@ -421,3 +421,49 @@ async def play_file(
     except Exception as e:
         logger.error(f"Error playing file: {e}")
         raise HTTPException(status_code=500, detail="Failed to play file")
+
+
+# Download Endpoint
+@router.get("/download")
+async def download_file(
+    folder_id: str = Query(..., description="Media folder ID"),
+    path: str = Query(..., description="File path relative to folder root (URL-encoded)"),
+    _: str = Depends(verify_token_or_query),
+):
+    """Download a media file.
+
+    Args:
+        folder_id: ID of the media folder.
+        path: Path to the file (URL-encoded, relative to folder root).
+
+    Returns:
+        File download response.
+
+    Raises:
+        HTTPException: If file not found or not a media file.
+    """
+    try:
+        decoded_path = unquote(path)
+        file_path = BrowserService.validate_path(folder_id, decoded_path)
+
+        if not file_path.is_file():
+            raise HTTPException(status_code=400, detail="Path is not a file")
+
+        if not BrowserService.is_media_file(file_path):
+            raise HTTPException(status_code=400, detail="File is not a media file")
+
+        return FileResponse(
+            path=file_path,
+            filename=file_path.name,
+            media_type="application/octet-stream",
+        )
+
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    except FileNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+    except HTTPException:
+        raise
+    except Exception as e:
+        logger.error(f"Error downloading file: {e}")
+        raise HTTPException(status_code=500, detail="Failed to download file")