feat: CI pipeline, lint fixes, and Renovate config

- pyproject.toml with ruff/pytest config (setuptools<81 pin)
- Full test suite (26 tests)
- Gitea Actions CI (lint, test, docker, notify)
- Ruff lint/format fixes across source files
- Renovate config for automated dependency updates

Ref: ADR-0057

renovate.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "local>daviestechlabs/renovate-config",
+    "local>daviestechlabs/renovate-config:python"
+  ]
+}