Bind claim delivery observation to mission beneficiary

[Manablaq]

What changed

• Bind persisted claim observations to the exact mission and beneficiary.
• Hide stale observations after a wallet switch instead of showing another wallet's parent claim.
• Keep external delivery observation read-only and fail-closed; no automatic retry is introduced.
• Add regression coverage for cross-mission and cross-beneficiary isolation.

Verification

• npm run typecheck
• npm run test
• npm run lint
• npm run build
• npm run test:e2e (12 passed)
• npm audit --audit-level=high
• direct GenLayer runtime: 578 passed, 334 subtests

Production deployment for this exact application commit is already READY at the canonical alias https://commit-protocol.vercel.app.