Replace the copilot-generated inline search logic with a claude-code-action
based architecture inspired by anthropic/claude-code's approach:
- Add .claude/commands/dedupe.md with 5-parallel-search strategy
- Add scripts/comment-on-duplicates.sh with 3-day grace period warning
- Rewrite issue-dedupe.yml to use claude-code-action + /dedupe command
- Rewrite autoclose script to check bot comments, human activity, and thumbsdown
- Rewrite backfill to trigger dedupe workflow per issue with rate limiting
- Add concurrency control, timeout, input validation, and rate limit retry
- Remove gh.sh (unnecessary), backfill-dedupe.js (replaced by workflow trigger)
