feat: add runtime state event spine

[devkade]

Summary

• Add versioned runtime state projection with fail-closed schema parsing and replay from structured runtime events.
• Add runtime event validation for objective/policy/graph/worker/claim/lease/evidence/evaluation/reward/final-report transitions.
• Add adapter-neutral agent adapter contract validation for Pi/Codex/Claude Code compatible worker substrates.
• Add MVP verification matrix covering schema, events, DAG readiness, claims/leases, worker heartbeat, policy/reward, integration retention, and storage evidence.
• Document the runtime spine and closeout matrix in the graph execution runtime boundary.

Issues

• Closes Design: define RunState schemas, versions, and migration policy #185
• Closes Design: define runtime event taxonomy, replay, and recovery semantics #186
• Addresses Design: define portable agent adapter and execution substrate contracts #188
• Addresses Design: define verification matrix for learning parallel runtime #191
• Addresses Sub-roadmap: DAG runtime phase 1 — task graph and readiness #194
• Addresses Sub-roadmap: DAG runtime phase 3 — worker execution, heartbeat, and evidence-gated completion #196
• Addresses Sub-roadmap: DAG runtime phase 2 — claim, lease, and stale ownership #197

Verification

• npm test -- test/runtime-state-events.test.ts
• npm run check
• npm run check:unused
• npm run quality:budgets
• npm run verify

Notes

• npm run quality:budgets passes with the existing non-failing code_smells warning (53 > 20) and coverage marked not configured.