Closes #312.

Summary

• add graph edge reaction handling for supersedes, contradicts, and extends
• stale target memories when active lifecycle edges apply, and restore reaction-owned changes when edges are removed, inactive, or negated
• register the state trigger and cover ambiguous graph-node targets, lifecycle cycles, and extend restoration behavior

Verification

• corepack pnpm exec vitest run --exclude test/integration.test.ts test/events-boundary.test.ts test/graph.test.ts test/graph-edge-reactions.test.ts
• corepack pnpm run lint
• corepack pnpm run build
• corepack pnpm test
• corepack pnpm exec vitest run --exclude test/integration.test.ts --no-file-parallelism --maxWorkers=1
• semgrep scan --config p/default --error --metrics=off .
• gitleaks protect --staged --redact
• gitleaks detect --source . --redact --no-git

Note: full-history gitleaks detect --source . --redact reports 14 pre-existing historical findings; current-tree and staged scans are clean.