refactor: migrate Deposit Agent from Assistants API to direct function calling

- Replace OpenAI Assistants API with direct function calling (AI Gateway)
- Add action-based parameters to manage_deposit tool (like manage_domain)
- Export executeDepositFunction for direct use in openai-service.ts
- Add formatDepositResult function for consistent response formatting
- Remove DEPOSIT_AGENT_ID dependency (no longer needed)
- Update CLAUDE.md documentation

Benefits:
- Bypasses regional restrictions via AI Gateway
- 100% consistent response formatting
- No Assistants API costs
- Faster execution (no thread creation)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/deposit-agent.ts

@@ -9,15 +9,15 @@
  * - [관리자] 대기 목록, 입금 확인/거절
  */
 
-interface DepositContext {
+export interface DepositContext {
   userId: number;
   telegramUserId: string;
   isAdmin: boolean;
   db: D1Database;
 }
 
-// 예치금 API 함수 실행
-async function executeDepositFunction(
+// 예치금 API 함수 실행 (export for direct use without Agent)
+export async function executeDepositFunction(
   funcName: string,
   funcArgs: Record<string, any>,
   context: DepositContext