feat: enrich listWaitingAgents with task/phase/initiative context via DB joins

Replaces the in-memory filter (agentManager.list() + filter) with a direct
repository query that LEFT JOINs tasks, phases, and initiatives to return
taskName, phaseName, initiativeName, and taskDescription alongside agent fields.

- Adds AgentWithContext interface and findWaitingWithContext() to AgentRepository port
- Implements findWaitingWithContext() in DrizzleAgentRepository using getTableColumns
- Wires agentRepository into TRPCContext, CreateContextOptions, and TrpcAdapterOptions
- Adds requireAgentRepository() helper following existing pattern
- Updates listWaitingAgents to use repository query instead of agentManager
- Adds 5 unit tests for findWaitingWithContext() covering all FK join edge cases
- Updates existing AgentRepository mocks to satisfy updated interface

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/server/db/repositories/drizzle/agent.test.ts

@@ -277,3 +277,91 @@ describe('DrizzleAgentRepository', () => {
     });
   });
 });
+
+describe('DrizzleAgentRepository.findWaitingWithContext()', () => {
+  let agentRepo: DrizzleAgentRepository;
+  let taskRepo: DrizzleTaskRepository;
+  let phaseRepo: DrizzlePhaseRepository;
+  let initiativeRepo: DrizzleInitiativeRepository;
+
+  beforeEach(() => {
+    const db = createTestDatabase();
+    agentRepo = new DrizzleAgentRepository(db);
+    taskRepo = new DrizzleTaskRepository(db);
+    phaseRepo = new DrizzlePhaseRepository(db);
+    initiativeRepo = new DrizzleInitiativeRepository(db);
+  });
+
+  it('returns empty array when no waiting agents exist', async () => {
+    const result = await agentRepo.findWaitingWithContext();
+    expect(result).toEqual([]);
+  });
+
+  it('only returns agents with status waiting_for_input', async () => {
+    await agentRepo.create({ name: 'running-agent', worktreeId: 'wt1', status: 'running' });
+    await agentRepo.create({ name: 'waiting-agent', worktreeId: 'wt2', status: 'waiting_for_input' });
+
+    const result = await agentRepo.findWaitingWithContext();
+    expect(result).toHaveLength(1);
+    expect(result[0].name).toBe('waiting-agent');
+  });
+
+  it('populates taskName, phaseName, initiativeName, taskDescription when FK associations exist', async () => {
+    const initiative = await initiativeRepo.create({ name: 'My Initiative' });
+    const phase = await phaseRepo.create({ initiativeId: initiative.id, name: 'Phase 1' });
+    const task = await taskRepo.create({
+      phaseId: phase.id,
+      name: 'Implement feature',
+      description: 'Write the feature code',
+    });
+
+    await agentRepo.create({
+      name: 'ctx-agent',
+      worktreeId: 'wt3',
+      status: 'waiting_for_input',
+      taskId: task.id,
+      initiativeId: initiative.id,
+    });
+
+    const result = await agentRepo.findWaitingWithContext();
+    expect(result).toHaveLength(1);
+    expect(result[0].taskName).toBe('Implement feature');
+    expect(result[0].phaseName).toBe('Phase 1');
+    expect(result[0].initiativeName).toBe('My Initiative');
+    expect(result[0].taskDescription).toBe('Write the feature code');
+  });
+
+  it('returns null for context fields when agent has no taskId or initiativeId', async () => {
+    await agentRepo.create({ name: 'bare-agent', worktreeId: 'wt4', status: 'waiting_for_input' });
+
+    const result = await agentRepo.findWaitingWithContext();
+    expect(result).toHaveLength(1);
+    expect(result[0].taskName).toBeNull();
+    expect(result[0].phaseName).toBeNull();
+    expect(result[0].initiativeName).toBeNull();
+    expect(result[0].taskDescription).toBeNull();
+  });
+
+  it('returns null phaseName when task has no phaseId', async () => {
+    const initiative = await initiativeRepo.create({ name: 'Orphan Init' });
+    const task = await taskRepo.create({
+      phaseId: null,
+      name: 'Orphan Task',
+      description: null,
+    });
+
+    await agentRepo.create({
+      name: 'orphan-agent',
+      worktreeId: 'wt5',
+      status: 'waiting_for_input',
+      taskId: task.id,
+      initiativeId: initiative.id,
+    });
+
+    const result = await agentRepo.findWaitingWithContext();
+    expect(result).toHaveLength(1);
+    expect(result[0].phaseName).toBeNull();
+    expect(result[0].taskName).toBe('Orphan Task');
+    expect(result[0].initiativeName).toBe('Orphan Init');
+  });
+});