M0: scaffold SPA + API monorepo

Backend (Django 6.1 + DRF):
- Token auth with a custom User model (register/login/logout/me)
- Library models (MediaItem, MediaLocation) and REST endpoints
- File list/detail with search, rating filter, sorting, pagination
- Multipart upload with optional rating/tags/notes
- Range-aware media serving (video seeking) and ffmpeg thumbnails
- scan_files management command for the watched folder

Frontend (React 19 + Vite + TypeScript):
- Catppuccin Mocha design tokens from the design docs
- App shell, token persistence, protected routes
- Library grid with filters, file detail with custom data editor
- Upload page with per-file progress via XHR
- Dev proxy to the Django API

backend/apps/library/urls.py

@@ -0,0 +1,12 @@
+from django.urls import include, path
+from rest_framework.routers import DefaultRouter
+
+from .views import MediaItemViewSet, UploadView
+
+router = DefaultRouter()
+router.register("files", MediaItemViewSet, basename="file")
+
+urlpatterns = [
+    path("", include(router.urls)),
+    path("uploads/", UploadView.as_view(), name="upload"),
+]