K Fleet v2.1.0

What changed

• Require a connected, repository-scoped Supermemory runtime before setup writes.
• Add a shared Engineering contract checkpoint for cross-boundary implementation,
  bug-fix, and refactor work.
• Require observable ownership, lifecycle, alternative, failure, deletion, and test
  decisions before production mutation.
• Strengthen design and verification checks so static analysis alone cannot prove
  changed behavior.
• Add a realistic cross-boundary calling regression case to the orchestration corpus.

Validation

• 30 orchestration corpus cases linted.
• 6 source-bound isolated blind release cases passed, including the new engineering
  checkpoint case.
• 22 Fleet Ledger fixture tests passed.
• Repository structure, forward-result hashes, skill validation, and GitHub CI passed.