style: fix import order in settings.py for ruff compliance

Move mimetypes import to the top of the import block to satisfy
ruff's import sorting rules (I001). The Windows mimetype fix from
PR #82 placed the import after other imports, which violated the
project's linting standards.

Changes:
- Move `import mimetypes` to alphabetically correct position
- Update comment to clarify timing requirement

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

server/routers/settings.py

@@ -6,6 +6,7 @@ API endpoints for global settings management.
 Settings are stored in the registry database and shared across all projects.
 """
 
+import mimetypes
 import os
 import sys
 from pathlib import Path
@@ -14,8 +15,7 @@ from fastapi import APIRouter
 
 from ..schemas import ModelInfo, ModelsResponse, SettingsResponse, SettingsUpdate
 
-# Mimetype fix for Windows
-import mimetypes
+# Mimetype fix for Windows - must run before StaticFiles is mounted
 mimetypes.add_type("text/javascript", ".js", True)
 
 # Add root to path for registry import