feat: add pipeline bridge for NATS to Argo/Kubeflow

- pipeline_bridge.py: Standalone bridge service
- pipeline_bridge_v2.py: handler-base version
- Supports Argo Workflows and Kubeflow Pipelines
- Workflow monitoring and status publishing
- Dockerfile variants for standalone and handler-base

.gitignore

@@ -0,0 +1,11 @@
+.venv/
+__pycache__/
+*.pyc
+*.pyo
+.pytest_cache/
+.mypy_cache/
+*.egg-info/
+dist/
+build/
+.env
+.env.local