feat: Cloudflare AI Gateway 적용

- OpenAI API 호출을 AI Gateway 경유로 변경
- 지역 제한 (403 unsupported_country_region_territory) 해결
- Gateway: telegram-bot (d8e5997eb4040f8b489f09095c0f623c)

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

src/openai-service.ts

@@ -1,6 +1,9 @@
 import type { Env } from './types';
 import { callDepositAgent } from './deposit-agent';
 
+// Cloudflare AI Gateway를 통해 OpenAI API 호출 (지역 제한 우회)
+const OPENAI_API_URL = 'https://gateway.ai.cloudflare.com/v1/d8e5997eb4040f8b489f09095c0f623c/telegram-bot/openai/chat/completions';
+
 interface OpenAIMessage {
   role: 'system' | 'user' | 'assistant' | 'tool';
   content: string | null;
@@ -250,7 +253,7 @@ async function suggestDomains(keywords: string, apiKey: string): Promise<string>
       const excludeList = [...checkedDomains].slice(-30).join(', ');
 
       // Step 1: GPT에게 도메인 아이디어 생성 요청
-      const ideaResponse = await fetch('https://api.openai.com/v1/chat/completions', {
+      const ideaResponse = await fetch(OPENAI_API_URL, {
         method: 'POST',
         headers: {
           'Content-Type': 'application/json',
@@ -836,7 +839,7 @@ async function executeTool(name: string, args: Record<string, string>, env?: Env
 
         if (hasKorean && env?.OPENAI_API_KEY) {
           try {
-            const translateRes = await fetch('https://api.openai.com/v1/chat/completions', {
+            const translateRes = await fetch(OPENAI_API_URL, {
               method: 'POST',
               headers: {
                 'Content-Type': 'application/json',
@@ -1090,7 +1093,7 @@ async function callOpenAI(
   messages: OpenAIMessage[],
   selectedTools?: typeof tools  // undefined = 도구 없음, 배열 = 해당 도구만 사용
 ): Promise<OpenAIResponse> {
-  const response = await fetch('https://api.openai.com/v1/chat/completions', {
+  const response = await fetch(OPENAI_API_URL, {
     method: 'POST',
     headers: {
       'Content-Type': 'application/json',