chore: add CI/CD pipeline for Gitea deployment

- Add .gitea/workflows/build.yml for tag-triggered builds
- Add Dockerfile for containerized deployment (port 8086)
- Add .dockerignore to keep image lean
- Add CHANGELOG.md following Keep a Changelog format
- Update AGENTS.md with deployment verification URL

Build pipeline:
1. Create Gitea release on v* tag
2. Build and push Docker image to git.schweitz.internal
3. Trigger Watchtower for automatic deployment

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,43 @@
+# Git
+.git
+.gitignore
+
+# Python
+__pycache__
+*.py[cod]
+*$py.class
+*.so
+.Python
+.venv
+venv
+ENV
+env
+
+# Testing
+.pytest_cache
+.coverage
+htmlcov
+tests/
+
+# IDE
+.idea
+.vscode
+*.swp
+*.swo
+
+# Logs
+logs/
+*.log
+
+# Environment
+.env
+.env.local
+.env.*.local
+
+# Development files
+*.md
+!README.md
+requirements-dev.txt
+implementation-plan.md
+fastapi-best-practices.md
+wakeup.sh