chore: add per-repo docs sync reminder

[hyldmo]

Summary

• add an executable per-repo PreToolUse Bash hook for numux documentation mirrors
• fire only for actual git commit commands when relevant dirty source/tooling paths lack README.md or CLAUDE.md changes
• preserve the existing Stop hook and emit additionalContext only, never permissionDecision

Payload proof

• plain commit: silent
• CLI source without README.md: specific docs reminder
• same source with README.md dirty: silent
• git log | grep commit: silent
• fired output contains no permissionDecision

Validation

• bun run fix
• bun run docs
• bun run typecheck
• bun run lint
• bun test
• bash -n .claude/hooks/docs-sync-reminder.sh
• jq empty .claude/settings.json

[github-actions]

🎉 This PR is included in version 2.19.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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