[EngSys] Update "ci-fix" and "pr-suppressions" docs, make AI-friendly

1. use agent to ingest existing docs, and any other data sources we can find (eg teams chat history), and generate new docs as MD files in the specs repo
2. review docs to ensure they align with latest best practices for mainstream specs, calling out exceptions as needed (eg fsv1/fsv2)
3. update skills/instructions to use docs

my ideal workflow:
1. you open a PR
2. checks run
3. copilot automatically analyzes your code changes, and your check results, and makes suggestions / gives approval
4. you can chat with copilot directly in your PR to collaborate to fix all checks, ask questions, etc