feat: make heartbeat trigger incremental reviews and suggest from graph changes

Heartbeat no longer writes its own report; it triggers the shared incremental review and, per plan intervention, derives evidence-backed suggestions from the review's graph changes. Manual review is incremental by default with explicit reanalysis. The Supervisor tab is renamed Smart heartbeat with heartbeat plans, and the redundant inner plan frame is removed.

src/main/assistant/supervision-production.test.ts

@@ -113,7 +113,7 @@ function fixture(content = 'Atlas and Beacon are separate projects.') {
   const now = Date.now()
   db.saveLocalConversations([{ header: { id: randomUUID(), projectId: db.listProjects()[0]!.id, title: 'Identity review', updatedAt: now },
     messages: [{ id: randomUUID(), role: 'user', state: 'complete', content, createdAt: now }] }])
-  const request: SupervisionRunRequest = { trigger: 'manual', scope: { kind: 'global' }, timeRange: {
+  const request: SupervisionRunRequest = { trigger: 'manual', reanalyze: true, scope: { kind: 'global' }, timeRange: {
     from: new Date(now - 1).toISOString(), to: new Date(now + 1).toISOString()
   } }
   const respond = vi.fn((prompt: string): unknown => {