Joe/docs update check work

[joe-clickhouse]

Summary

The PR Adds docs drift check on pull requests as an advisory CI check that flags PRs that change user facing code without updating docs/ or README.md.

The new docs_drift_check.yml workflow calls the shared claude-docs-drift workflow in integrations-shared-workflows. Claude reads the PR diff and applies the rubric in the repo's own .claude/agents/docs-drift-reviewer.md in report only
mode. When a user visible change is missing a doc update, the workflow applies the needs-docs label and posts one sticky comment naming the change and where the update belongs. Every push re-runs the check. Once the docs
are updated the label is removed and the comment is marked resolved.

The check never blocks a merge. Fork PRs are skipped and a maintainer can run one manually via workflow_dispatch with the PR number.

This is separate from docs_sync.yml, which ships docs/ to the aggregator repo, and docs_verify.yml, which validates the Mintlify build. This check catches code changes that land without their matching doc updates.

The rubric also works locally as a Claude Code agent in fix mode, where it edits the docs instead of only reporting.

Depends on the claude-docs-drift workflow PR in integrations-shared-workflows.