KanBorg 1.2.27 — phase checkpoints and stable signing

KanBorg now saves structured phase checkpoints at stage transitions, completed implementation, passed QA, and merge boundaries. Follow-ups consume the checkpoint once and start fresh model context in the same run and worktree. Task history, exact commit/check/review references, and unresolved constraints remain available through the recorded evidence.

Routed workers recover from a context-limit rejection using a bounded background envelope and a reference to the full saved session. Recovery occurs only before useful output or tool execution, with bounded retries. It does not restart ambiguous work or create a duplicate worker. External coordinators receive checkpoint guidance; their own chat compaction depends on their harness.

macOS builds now require the stable Developer ID signature instead of ad-hoc signing, preserving the app identity used by Keychain. Existing storage identifiers and saved connections remain unchanged. A one-time Keychain approval may still be needed after migration. This release is signed but not notarized.

Validation: 119 desktop tests, 9 supervisor tests, and desktop TypeScript check passed. Developer ID signature verification, DMG integrity verification, and isolated legacy-installer startup/recovery checks passed; the project was restored and an external coordinator resume request was durably queued. This release does not claim to resolve the separate multi-project runtime retention or dispatch-timeout reporting issues.