Fix repository AT-URI to use record rkey instead of name
Issue records were not appearing on tangled.org because the repo field
used an incorrect AT-URI format with the repository name as the rkey
instead of the actual record key.
Changes:
- Update buildRepoAtUri() to query PDS for sh.tangled.repo records
- Find matching repository by name field in record value
- Return record's URI which contains the correct rkey
- Add comprehensive tests for new query-based resolution
Before: at://did:plc:xxx/sh.tangled.repo/tangled-cli
After: at://did:plc:xxx/sh.tangled.repo/3mef23waqwq22
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>