✨(all) add organizations, resources, channels, and infra migration (#34)

Add multi-tenant organization model populated from OIDC claims with
org-scoped user discovery, CalDAV principal filtering, and cross-org
isolation at the SabreDAV layer.

Add bookable resource principals (rooms, equipment) with CalDAV
auto-scheduling that handles conflict detection, auto-accept/decline,
and org-scoped booking enforcement. Fixes #14.

Replace CalendarSubscriptionToken with a unified Channel model
supporting CalDAV integration tokens and iCal feed URLs, with
encrypted token storage and role-based access control. Fixes #16.

Migrate task queue from Celery to Dramatiq with async ICS import,
progress tracking, and task status polling endpoint.

Replace nginx with Caddy for both the reverse proxy and frontend
static serving. Switch frontend package manager from yarn/pnpm to
npm and upgrade Node to 24, Next.js to 16, TypeScript to 5.9.

Harden security with fail-closed entitlements, RSVP rate limiting
and token expiry, CalDAV proxy path validation blocking internal
API routes, channel path scope enforcement, and ETag-based
conflict prevention.

Add frontend pages for resource management and integration channel
CRUD, with resource booking in the event modal.

Restructure CalDAV paths to /calendars/users/ and
/calendars/resources/ with nested principal collections in SabreDAV.

.github/workflows/calendars.yml

@@ -65,6 +65,7 @@ jobs:
       CALDAV_URL: http://localhost:80
       CALDAV_OUTBOUND_API_KEY: test-outbound-key
       CALDAV_INBOUND_API_KEY: test-inbound-key
+      CALDAV_INTERNAL_API_KEY: test-internal-key
       CALDAV_CALLBACK_HOST: localhost
       TRANSLATIONS_JSON_PATH: ${{ github.workspace }}/src/frontend/apps/calendars/src/features/i18n/translations.json
 
@@ -80,7 +81,7 @@ jobs:
       - name: Build and start CalDAV server
         working-directory: .
         run: |
-          docker build -t caldav-test docker/sabredav
+          docker build -t caldav-test src/caldav
           docker run -d --name caldav-test \
             --network host \
             -e PGHOST=localhost \
@@ -88,9 +89,10 @@ jobs:
             -e PGDATABASE=calendars \
             -e PGUSER=pgroot \
             -e PGPASSWORD=pass \
-            -e CALDAV_BASE_URI=/api/v1.0/caldav/ \
+            -e CALDAV_BASE_URI=/caldav/ \
             -e CALDAV_INBOUND_API_KEY=test-inbound-key \
             -e CALDAV_OUTBOUND_API_KEY=test-outbound-key \
+            -e CALDAV_INTERNAL_API_KEY=test-internal-key \
             caldav-test \
             sh -c "/usr/local/bin/init-database.sh && apache2-foreground"
 
@@ -108,13 +110,10 @@ jobs:
       - name: Install the dependencies
         run: uv sync --locked --all-extras
 
-      - name: Install gettext (required to compile messages) and MIME support
+      - name: Install MIME support
         run: |
           sudo apt-get update
-          sudo apt-get install -y gettext pandoc shared-mime-info media-types
-
-      - name: Generate a MO file from strings extracted from the project
-        run: uv run python manage.py compilemessages
+          sudo apt-get install -y pandoc shared-mime-info media-types
 
       - name: Run tests
         run: uv run pytest -n 2