fix: resolve do:pr rebase conflicts autonomously

[atomantic]

Summary

• make required do:pr rebases resolve conflicts and continue instead of stopping at the first conflict
• add a shared resolution playbook that preserves human-authored intent and regenerates derived artifacts from canonical inputs
• apply the same behavior to reviewer push retries and bundle the playbook into supported Agent Skills installations
• add regression coverage for the workflow, installer allowlists, and deferred library bundling

Validation

• npm test — 429 tests passed
• node bin/cli.js --list
• node bin/cli.js --dry-run
• git diff --check main...HEAD

Review

• required local code review completed with no findings
• no external reviewer was configured for this run