fix: register MIME types for CSS/JS/SVG in Docker

Docker slim images may have incomplete mimetypes database, causing
static files to be served without proper Content-Type headers.
Explicitly register common web asset MIME types at module load.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: JacobCoffee

src/scribbl_py/app.py

@@ -6,6 +6,7 @@
 
 from __future__ import annotations
 
+import mimetypes
 import os
 from contextlib import asynccontextmanager
 from typing import TYPE_CHECKING
@@ -27,6 +28,12 @@
 if TYPE_CHECKING:
     from collections.abc import AsyncGenerator
 
+# Register MIME types for static file serving (Docker slim images may have incomplete mimetypes)
+mimetypes.add_type("text/css", ".css")
+mimetypes.add_type("application/javascript", ".js")
+mimetypes.add_type("image/svg+xml", ".svg")
+mimetypes.add_type("application/json", ".json")
+
 
 @asynccontextmanager
 async def lifespan(app: Litestar) -> AsyncGenerator[None, None]: