Implements federation trust model for multi-repo type validation:
- Built-in types are validated (catch typos)
- Non-built-in types trusted from source repos
Changes:
- Add IssueType.IsBuiltIn() method
- Add Issue.ValidateForImport() for trust-based validation
- Update upsertIssueInTx to use ValidateForImport
Closes: bd-dqwuf, bd-alpw2 | Epic: bd-9ji4z
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
576a517c59