Add OpenMetadata PR impact analysis action

[PRADDZY]

Summary

• Adds a reusable OpenMetadata impact-analysis composite GitHub Action for dbt model/schema pull requests.
• Refactors the MCP impact-analysis cookbook into testable parser, scorer, renderer, and CLI modules with deterministic fallback output.
• Updates the demo workflow and cookbook docs so the action posts a sticky PR comment and uploads Markdown/HTML/JSON artifacts.

Why

This turns the existing demo workflow for open-metadata/OpenMetadata#26648 into a reusable CI/CD path that answers "what breaks if I change this?" before a dbt change is merged. It keeps OpenMetadata access read-only and degrades to a review checklist when AI credentials are unavailable.

Validation

• python -m pytest cookbook\mcp-impact-analysis\tests -q -> 7 passed
• python -m pytest tests/test_mcp_models.py tests/test_mcp_langchain.py -q from python/ -> 14 passed
• python -m ruff check cookbook\mcp-impact-analysis -> All checks passed
• YAML parse check for .github/actions/openmetadata-impact-analysis/action.yml and .github/workflows/impact-analysis.yml -> yaml ok
• CLI smoke test on cookbook\mcp-impact-analysis\example_changes.diff with --no-ai produced risk_level: medium and affected_count: 0

Notes

• actionlint was not available in the local environment, so GitHub Actions semantic linting was not run locally.

[Copilot]

Pull request overview

This PR turns the existing MCP impact-analysis cookbook into a reusable CI component by introducing a composite GitHub Action that runs a refactored analyzer (parser/scorer/renderer/CLI) and posts a sticky PR comment plus artifacts.

Changes:

• Added a composite GitHub Action to run impact analysis and expose risk-level / affected-count outputs.
• Refactored the cookbook analyzer into diff_parser, risk_scoring, report_renderer, and an updated batch_analyzer CLI with deterministic fallback.
• Updated the demo workflow and cookbook docs; added unit tests for the new modules.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
.github/actions/openmetadata-impact-analysis/action.yml	New composite action to run the analyzer and publish outputs/artifacts.
.github/workflows/impact-analysis.yml	Workflow now triggers on dbt model/schema changes, runs the composite action, and posts a sticky PR comment + artifacts.
cookbook/mcp-impact-analysis/batch_analyzer.py	Refactored CLI entrypoint with deterministic fallback, HTML/JSON outputs, and risk scoring.
cookbook/mcp-impact-analysis/diff_parser.py	New diff-to-asset parsing logic with path filtering and change-type detection.
cookbook/mcp-impact-analysis/risk_scoring.py	New deterministic scoring based on affected asset links and risk keywords.
cookbook/mcp-impact-analysis/report_renderer.py	New Markdown/HTML report rendering with a stable comment marker and escaping.
cookbook/mcp-impact-analysis/README.md	Updated usage/docs to describe the new action, outputs, and fallback behavior.
cookbook/mcp-impact-analysis/tests/*	New tests covering parser, renderer escaping, scoring, and CLI behavior.

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