✨(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.

CLAUDE.md

@@ -18,44 +18,39 @@ In this project, you can create events, invite people to events, create calendar
 ### Development Setup
 ```bash
 make bootstrap          # Initial setup: builds containers, runs migrations, starts services
-make run                # Start all services (backend + frontend containers)
-make run-backend        # Start backend services only (for local frontend development)
+make start              # Start all services (backend + frontend containers)
+make start-back         # Start backend services only (for local frontend development)
 make stop               # Stop all containers
 make down               # Stop and remove containers, networks, volumes
+make update             # Update project after pulling changes
 ```
 
 ### Backend Development
 ```bash
 make test-back -- path/to/test.py::TestClass::test_method  # Run specific test
 make test-back-parallel                                     # Run all tests in parallel
-make lint                                                   # Run ruff + pylint
+make lint                                                   # Run all linters (back + front)
+make lint-back                                              # Run back-end linters only
 make migrate                                                # Run Django migrations
 make makemigrations                                         # Create new migrations
-make shell                                                  # Django shell
-make dbshell                                                # PostgreSQL shell
+make shell-back-django                                      # Django shell
+make shell-db                                               # PostgreSQL shell
 ```
 
 ### Frontend Development
 ```bash
-make frontend-development-install   # Install frontend dependencies locally
-make run-frontend-development       # Run frontend locally (after run-backend)
-make frontend-lint                  # Run ESLint on frontend
-cd src/frontend/apps/calendars && yarn test              # Run frontend tests
-cd src/frontend/apps/calendars && yarn test:watch        # Watch mode
+make install-front      # Install frontend dependencies
+make lint-front         # Run ESLint on frontend
+make typecheck-front    # Run TypeScript type checker
+make test-front         # Run frontend tests
+cd src/frontend/apps/calendars && npm test              # Run frontend tests (local)
+cd src/frontend/apps/calendars && npm run test:watch    # Watch mode (local)
 ```
 
 ### E2E Tests
 ```bash
-make run-tests-e2e                           # Run all e2e tests
-make run-tests-e2e -- --project chromium --headed  # Run with specific browser
-```
-
-### Internationalization
-```bash
-make i18n-generate         # Generate translation files
-make i18n-compile          # Compile translations
-make crowdin-upload        # Upload sources to Crowdin
-make crowdin-download      # Download translations from Crowdin
+make test-e2e                                    # Run all e2e tests
+make test-e2e -- --project chromium --headed     # Run with specific browser
 ```
 
 ## Architecture
@@ -70,14 +65,14 @@ make crowdin-download      # Download translations from Crowdin
   - `tests/` - pytest test files
 
 ### Frontend Structure (`src/frontend/`)
-Yarn workspaces monorepo:
+npm workspaces:
 - `apps/calendars/` - Main Next.js application
   - `src/features/` - Feature modules (calendar, auth, api, i18n, etc.)
   - `src/pages/` - Next.js pages
   - `src/hooks/` - Custom React hooks
 - `apps/e2e/` - Playwright end-to-end tests
 
-### CalDAV Server (`docker/sabredav/`)
+### CalDAV Server (`src/caldav/`)
 PHP SabreDAV server providing CalDAV protocol support, running against the shared PostgreSQL database.
 
 **IMPORTANT: Never query the SabreDAV database tables directly from Django.** Always interact with CalDAV through the SabreDAV HTTP API (PROPFIND, REPORT, PUT, etc.).
@@ -86,14 +81,13 @@ PHP SabreDAV server providing CalDAV protocol support, running against the share
 
 | Service | URL / Port | Description |
 |---------|------------|-------------|
-| **Frontend** | [http://localhost:8920](http://localhost:8920) | Next.js Calendar frontend |
-| **Backend API** | [http://localhost:8921](http://localhost:8921) | Django REST API |
-| **CalDAV** | [http://localhost:8922](http://localhost:8922) | SabreDAV CalDAV server |
-| **Nginx** | [http://localhost:8923](http://localhost:8923) | Reverse proxy (frontend + API) |
-| **Redis** | 8924 | Cache and Celery broker |
-| **Keycloak** | [http://localhost:8925](http://localhost:8925) | OIDC identity provider |
-| **PostgreSQL** | 8926 | Database server |
-| **Mailcatcher** | [http://localhost:8927](http://localhost:8927) | Email testing interface |
+| **Frontend** | [http://localhost:8930](http://localhost:8930) | Next.js Calendar frontend |
+| **Backend API** | [http://localhost:8931](http://localhost:8931) | Django REST API |
+| **CalDAV** | [http://localhost:8932](http://localhost:8932) | SabreDAV CalDAV server |
+| **Redis** | 8934 | Cache and Celery broker |
+| **Keycloak** | [http://localhost:8935](http://localhost:8935) | OIDC identity provider |
+| **PostgreSQL** | 8936 | Database server |
+| **Mailcatcher** | [http://localhost:8937](http://localhost:8937) | Email testing interface |
 
 ## Key Technologies