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/trpc/context.ts

@@ -20,6 +20,7 @@ import type { ConversationRepository } from '../db/repositories/conversation-rep
 import type { ChatSessionRepository } from '../db/repositories/chat-session-repository.js';
 import type { ReviewCommentRepository } from '../db/repositories/review-comment-repository.js';
 import type { ErrandRepository } from '../db/repositories/errand-repository.js';
+import type { AgentRepository } from '../db/repositories/agent-repository.js';
 import type { AccountCredentialManager } from '../agent/credentials/types.js';
 import type { DispatchManager, PhaseDispatchManager } from '../dispatch/types.js';
 import type { CoordinationManager } from '../coordination/types.js';
@@ -87,6 +88,8 @@ export interface TRPCContext {
   projectSyncManager?: ProjectSyncManager;
   /** Absolute path to the workspace root (.cwrc directory) */
   workspaceRoot?: string;
+  /** Agent repository for enriched queries (e.g., findWaitingWithContext) */
+  agentRepository?: AgentRepository;
 }
 
 /**
@@ -119,6 +122,7 @@ export interface CreateContextOptions {
   errandRepository?: ErrandRepository;
   projectSyncManager?: ProjectSyncManager;
   workspaceRoot?: string;
+  agentRepository?: AgentRepository;
 }
 
 /**
@@ -155,5 +159,6 @@ export function createContext(options: CreateContextOptions): TRPCContext {
     errandRepository: options.errandRepository,
     projectSyncManager: options.projectSyncManager,
     workspaceRoot: options.workspaceRoot,
+    agentRepository: options.agentRepository,
   };
 }