fix: Update GitHub and Gitea workflows for Python 3.13 and MongoDB

Changes to GitHub Actions (.github/workflows/build-deploy.yml):
- Update PYTHON_VERSION from 3.11 to 3.13

Changes to Gitea Actions (.gitea/workflows/ci.yml):
- Update PYTHON_VERSION from 3.10 to 3.13
- Update POETRY_VERSION from 1.7.1 to 1.8.0
- Replace PostgreSQL and Redis services with MongoDB
- Update service health check for MongoDB (mongosh)
- Update test environment variables for MongoDB
- Remove DATABASE_URL and REDIS_URL
- Add MONGODB_URL and MONGODB_DATABASE

This ensures all CI/CD pipelines are aligned with:
- Python 3.13 requirement in pyproject.toml
- MongoDB migration from PostgreSQL

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

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

.github/workflows/build-deploy.yml

@@ -26,7 +26,7 @@ on:
 env:
   DOCKER_REGISTRY: ghcr.io
   IMAGE_NAME: ${{ github.repository }}/docs-server
-  PYTHON_VERSION: '3.11'
+  PYTHON_VERSION: '3.13'
 
 jobs:
   # Job 1: Linting e validazione