Prepare Matrix for migration and improve service health checks

- Updated .gitignore to selectively track Matrix config files
  - Allow: homeserver.yaml, *.log.config
  - Exclude: *.db*, media_store/, signing keys
- Added Matrix configuration files to repository
- Fixed BookStack environment variables (APP_KEY, DB_* pattern)
- Improved health checks for BookStack, JupyterHub, and Synapse
- All services now have proper health monitoring

matrix/data/homeserver.yaml

@@ -0,0 +1,30 @@
+# Configuration file for Synapse.
+
+server_name: "einszwovier.local"
+pid_file: /data/homeserver.pid
+listeners:
+  - port: 8008
+    tls: false
+    type: http
+    x_forwarded: true
+    resources:
+      - names: [client, federation]
+        compress: false
+database:
+  name: sqlite3
+  args:
+    database: /data/homeserver.db
+
+# Connection and performance settings
+max_upload_size: 50M
+url_preview_enabled: false
+
+log_config: "/data/localhost.log.config"
+media_store_path: /data/media_store
+registration_shared_secret: "D2mw3LqNKe98ga-pYO1l5KbXf^jgx&s5yjq&ipAGjln:AzLag8"
+report_stats: false
+macaroon_secret_key: "T26aaiHWLHbm+P6fi_8:VXTIn0W_kHH__CQAdhPyaLhBe~OG*_"
+form_secret: "k,C38Dw^6b8Y+9-cSQpLb@GPoS*1POr8GDWXsLMKLHEU2+&q-@"
+signing_key_path: "/data/localhost.signing.key"
+trusted_key_servers:
+  - server_name: "matrix.org"