Improve logging and infrastructure variable consistency

Changes:
- Migrate Authentik to journald logging (remove file-based logs)
- Update Gitea to use infrastructure variables for PostgreSQL access
- Add comprehensive logging documentation to deployment guide
- Add infrastructure variable pattern guide to integration docs

Authentik Logging:
- Remove LogDriver=k8s-file from server and worker containers
- Remove logs directory creation from user setup tasks
- Update deployment guide with journald examples and JSON log patterns

Gitea Infrastructure Variables:
- Add infrastructure dependencies section to role defaults
- Replace hardcoded paths with postgresql_unix_socket_directories variable
- Replace hardcoded 'postgres' group with postgresql_client_group variable
- Add infrastructure variable validation in tasks
- Remove manual socket permission override (handled by infrastructure)

Documentation:
- Add journald logging best practices to service integration guide
- Add infrastructure variable pattern documentation with Gitea example
- Update Authentik deployment guide with journald commands and JSON filtering
- Document benefits: centralized logging, single source of truth, maintainability

Validated on arch-vps:
- Authentik logs accessible via journalctl and podman logs (identical output)
- Gitea user added to postgres-clients group (GID 962)
- No PostgreSQL socket permission errors after service restart

docs/authentik-deployment-guide.md

@@ -453,35 +453,64 @@ curl -v https://auth.jnss.me/
 
 #### Key Log Locations
 
-```bash
-# Authentik application logs
-ssh root@your-vps "cat /opt/authentik/logs/server.log"
-ssh root@your-vps "cat /opt/authentik/logs/worker.log"
+Authentik uses **journald** for centralized logging. Both `journalctl` and `podman logs` provide access to the same log stream:
 
-# systemd service logs
+```bash
+# View Authentik logs via journalctl (system-wide logging)
 ssh root@your-vps "journalctl -u authentik-server -f"
 ssh root@your-vps "journalctl -u authentik-worker -f"
 
+# View Authentik logs via podman (container-specific)
+ssh root@your-vps "podman logs -f authentik-server"
+ssh root@your-vps "podman logs -f authentik-worker"
+
+# View recent logs with timestamp (last 50 lines)
+ssh root@your-vps "journalctl -u authentik-server --lines 50 --no-pager"
+
+# Filter logs by time
+ssh root@your-vps "journalctl -u authentik-server --since '10 minutes ago'"
+ssh root@your-vps "journalctl -u authentik-server --since '2025-12-14 16:00:00'"
+
+# Search logs for specific patterns
+ssh root@your-vps "journalctl -u authentik-server | grep ERROR"
+ssh root@your-vps "journalctl -u authentik-worker | grep 'database connection'"
+
 # Caddy logs for reverse proxy issues
 ssh root@your-vps "journalctl -u caddy -f"
 ```
 
+**Note**: Logs are in JSON format with structured fields (timestamp, level, logger, event, etc.).
+
 #### Common Log Patterns
 
-**Successful startup**:
-```
-INFO     authentik.core.signals: authentik 2025.10.x starting
-INFO     authentik.core.models: Database version up-to-date
+Authentik logs are in **JSON format** for structured analysis. Here are common patterns:
+
+**Successful API request**:
+```json
+{"auth_via": "secret_key", "domain_url": "0.0.0.0", "event": "/api/v3/outposts/proxy/", 
+ "level": "info", "logger": "authentik.asgi", "method": "GET", "status": 200, 
+ "timestamp": "2025-12-14T16:13:17.269312"}
 ```
 
-**Database connection success**:
-```
-INFO     authentik.core.db: Connected to database via unix socket
+**Startup and initialization**:
+```json
+{"event": "updating brand certificates", "level": "info", 
+ "logger": "authentik.router.brand_tls", "timestamp": "2025-12-14T16:13:17Z"}
 ```
 
-**Cache connection success**:
+**Warning patterns**:
+```json
+{"event": "No providers assigned to this outpost, check outpost configuration", 
+ "level": "warning", "logger": "authentik.outpost.proxyv2"}
 ```
-INFO     authentik.core.cache: Connected to cache via unix socket
+
+**Filtering JSON logs by level**:
+```bash
+# Filter by error level
+ssh root@your-vps "journalctl -u authentik-server --since today | grep '\"level\":\"error\"'"
+
+# Filter by specific event
+ssh root@your-vps "journalctl -u authentik-server | grep '\"event\":\"database connection\"'"
 ```
 
 ## Performance Monitoring