docs: tighten incident runbook evidence package

[bingmokaka]

Summary

Adds a repository-specific incident evidence package checklist to the operations runbook and removes the duplicate Incident Runbook entry from the operations guide.

Fixes #1

Changes

• Added docs/INCIDENT_RUNBOOK.md evidence package table covering build diagnostics, health snapshots, deployment history, migration state, and OpenAPI comparison output.
• Explicitly calls out that diagnostic/build-00000000.* files are stubs and not valid incident or payout evidence.
• Removed the duplicated Incident Runbook bullet from docs/OPERATIONS.md while keeping the repository-local link.
• Added real validation artifacts: diagnostic/build-d5f530ae.json and diagnostic/build-d5f530ae.logd.

Testing

• python3 build.py was attempted first but was not available on this Windows environment.
• PYTHONIOENCODING=utf-8 python build.py using the bundled Python completed diagnostic finalization and generated diagnostic/build-d5f530ae.json plus diagnostic/build-d5f530ae.logd.
• The module builds failed because this environment is missing cargo, npm, go, gcc, g++, cmake, make, javac, ruby, luac, and ghc; the diagnostic artifacts capture those failures.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

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• I would like to request that my diagnostic build log is removed before merging