feat: add Linkwarden bookmark manager stack

Added new Links stack to Falcon infrastructure:

**Links Stack (links.pivoine.art):**
- Linkwarden bookmark manager with PostgreSQL backend
- Meilisearch v1.12.8 for full-text search
- Browser extension support
- Screenshot and PDF archiving
- Collaborative bookmark sharing

**Infrastructure Updates:**
- Created links/compose.yaml with linkwarden and meilisearch services
- Added linkwarden database to PostgreSQL init script
- Added LINKS_* environment variables to arty.yml
- Updated compose.yaml to include links stack
- Cleaned up .env to contain only secrets
- Added all EMAIL_* variables to .env

**Documentation:**
- Updated CLAUDE.md with Links service details
- Updated README.md with Links in CORE SYSTEMS table
- Added linkwarden_data and meili_data volumes to docs

**Required Secrets (in .env):**
- LINKS_NEXTAUTH_SECRET: NextAuth.js session encryption
- LINKS_MEILI_MASTER_KEY: Meilisearch API authentication

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

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

core/postgres/init/01-init-databases.sh

@@ -21,15 +21,20 @@ psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "$POSTGRES_DB" <<-E
     SELECT 'CREATE DATABASE n8n'
     WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'n8n')\gexec
 
+    -- Linkwarden bookmark manager database
+    SELECT 'CREATE DATABASE linkwarden'
+    WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'linkwarden')\gexec
+
     -- Grant privileges to all databases
     GRANT ALL PRIVILEGES ON DATABASE directus TO $POSTGRES_USER;
     GRANT ALL PRIVILEGES ON DATABASE umami TO $POSTGRES_USER;
     GRANT ALL PRIVILEGES ON DATABASE n8n TO $POSTGRES_USER;
+    GRANT ALL PRIVILEGES ON DATABASE linkwarden TO $POSTGRES_USER;
 
     -- Log success
     SELECT 'Compose databases initialized:' AS status;
     SELECT datname FROM pg_database
-    WHERE datname IN ('directus', 'umami', 'n8n')
+    WHERE datname IN ('directus', 'umami', 'n8n', 'linkwarden')
     ORDER BY datname;
 EOSQL
 
@@ -41,4 +46,5 @@ echo "Databases available:"
 echo "  • directus     - Sexy application database"
 echo "  • umami        - Tracking database"
 echo "  • n8n          - Workflow automation database"
+echo "  • linkwarden   - Bookmark manager database"
 echo ""