feat: add Tandoor recipe manager to infrastructure

Added Tandoor Recipes as a comprehensive recipe management solution:

**Tandoor Stack** (tandoor.pivoine.art):
- Modern recipe manager with smart scaling and collaboration
- PostgreSQL backend for recipe persistence
- Email notifications via IONOS SMTP
- Static and media file storage in dedicated volumes
- User signups disabled (admin-only access)

**Features:**
- Smart recipe scaling (auto-adjust ingredients for servings)
- Spaces for collaboration (family/roommate recipe sharing)
- Meal planning and shopping lists
- Recipe import from URLs
- Mobile app support (Kitshn app)
- Nutritional information and pricing

**Infrastructure updates:**
- Added tandoor database to PostgreSQL init script
- Added environment variables to arty.yml
- Updated compose.yaml include list
- Added Tandoor volumes (staticfiles, mediafiles) to Restic backup
- Configured email notifications for invitations and notifications

**Tech stack:**
- Django/Python backend
- Vue.js frontend
- PostgreSQL database (shared core instance)
- Gunicorn WSGI server

Tandoor provides superior UX compared to Mealie with better recipe
scaling, collaboration features, and mobile app experience.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

restic/compose.yaml

@@ -23,6 +23,8 @@ services:
       - backup_mattermost_config:/volumes/mattermost_config:ro
       - backup_mattermost_data:/volumes/mattermost_data:ro
       - backup_mattermost_plugins:/volumes/mattermost_plugins:ro
+      - backup_tandoor_staticfiles:/volumes/tandoor_staticfiles:ro
+      - backup_tandoor_mediafiles:/volumes/tandoor_mediafiles:ro
       - backup_scrapyd_data:/volumes/scrapyd_data:ro
       - backup_scrapy_code:/volumes/scrapy_code:ro
       - backup_n8n_data:/volumes/n8n_data:ro
@@ -95,6 +97,12 @@ volumes:
   backup_mattermost_plugins:
     name: mattermost_plugins
     external: true
+  backup_tandoor_staticfiles:
+    name: tandoor_staticfiles
+    external: true
+  backup_tandoor_mediafiles:
+    name: tandoor_mediafiles
+    external: true
   backup_scrapyd_data:
     name: scrapy_scrapyd_data
     external: true