fix: Gitea Traefik routing and connection pool optimization

- Remove middleware reference from Gitea Traefik labels (caused routing issues)
- Optimize Gitea connection pool settings (MAX_IDLE_CONNS=30, authentication_timeout=180s)
- Add explicit service reference in Traefik labels
- Fix intermittent 504 timeouts by improving PostgreSQL connection handling

Fixes Gitea unreachability via git.michaelschiemer.de

deployment/stacks/gitea/README.md

@@ -177,9 +177,10 @@ The playbook will:
 ### Configuration File
 
 Gitea configuration is managed via `app.ini` file:
-- **Local file**: `deployment/stacks/gitea/app.ini` (for local development)
-- **Production**: Generated from Ansible template `deployment/ansible/templates/gitea-app.ini.j2`
-- The `app.ini` is mounted read-only into the container at `/data/gitea/conf/app.ini`
+- **Template**: `deployment/ansible/templates/gitea-app.ini.j2` (Ansible template)
+- **Production**: Generated from template and deployed via Ansible playbook `setup-gitea-initial-config.yml`
+- The `app.ini` is copied to the container at `/data/gitea/conf/app.ini`
+- **Important**: `app.ini` is a minimal configuration. Cache, Session, Queue, and other settings are controlled via `GITEA__...` environment variables in `docker-compose.yml` which override `app.ini` settings on every container start.
 - Configuration is based on the official Gitea example: https://github.com/go-gitea/gitea/blob/main/custom/conf/app.example.ini
 
 **Key Configuration Sections:**