feat(19-01): export PendingQuestions and QuestionItem from shared package

- Re-export PendingQuestions and QuestionItem types from agent/types
- Available via @codewalk-district/shared for frontend consumption

packages/shared/src/index.ts

@@ -1,2 +1,2 @@
 export type { AppRouter } from './trpc.js';
-export type { Initiative, Phase, Plan, Task, Agent, Message } from './types.js';
+export type { Initiative, Phase, Plan, Task, Agent, Message, PendingQuestions, QuestionItem } from './types.js';

packages/shared/src/types.ts

@@ -1 +1,2 @@
 export type { Initiative, Phase, Plan, Task, Agent, Message } from '../../../src/db/schema.js';
+export type { PendingQuestions, QuestionItem } from '../../../src/agent/types.js';