✨(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.

bin/scalingo_run_web

@@ -3,6 +3,11 @@
 # Parse DATABASE_URL into PG* vars for PHP and psql
 source bin/export_pg_vars.sh
 
+# Set defaults for Caddy env vars
+export CALENDARS_FRONTEND_ROOT="${CALENDARS_FRONTEND_ROOT:-/app/build/frontend-out}"
+export CALENDARS_FRONTEND_BACKEND_SERVER="${CALENDARS_FRONTEND_BACKEND_SERVER:-localhost:8000}"
+export DJANGO_ADMIN_URL="${DJANGO_ADMIN_URL:-admin}"
+
 # Start PHP-FPM for SabreDAV (CalDAV server)
 .php/usr/sbin/php-fpm8.3 \
   -n -c /app/.php/php.ini \
@@ -12,11 +17,11 @@ source bin/export_pg_vars.sh
 # Start the Django backend
 gunicorn -b :8000 calendars.wsgi:application --log-file - &
 
-# Start the Nginx server
-bin/run &
+# Start the Caddy server
+bin/caddy run --config Caddyfile --adapter caddyfile &
 
 # if the current shell is killed, also terminate all its children
-trap "pkill SIGTERM -P $$" SIGTERM
+trap "pkill -SIGTERM -P $$" SIGTERM
 
 # wait for a single child to finish,
 wait -n