refactor: migrate troubleshoot-agent from KV to D1

- Create troubleshoot_sessions table in D1
- Replace KV session storage with D1
- Unify field names to snake_case (user_id, collected_info, created_at, updated_at, expires_at)
- Add __PASSTHROUGH__/__SESSION_END__ marker support
- Change handler signature to match domain/deposit pattern
- Extract system prompt to constant TROUBLESHOOT_EXPERT_PROMPT
- Add hasTroubleshootSession() for routing
- Update openai-service.ts to use new D1-based functions
- Update troubleshoot-tool.ts to use D1 instead of KV
- Add TroubleshootSessionStatus type

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

src/tools/troubleshoot-tool.ts

@@ -31,37 +31,30 @@ export async function executeManageTroubleshoot(
 
   logger.info('트러블슈팅 도구 호출', { action, userId: telegramUserId });
 
-  if (!env?.SESSION_KV || !telegramUserId) {
+  if (!env?.DB || !telegramUserId) {
     return '🚫 트러블슈팅 기능을 사용할 수 없습니다.';
   }
 
-  const { getTroubleshootSession, saveTroubleshootSession, deleteTroubleshootSession } = await import('../agents/troubleshoot-agent');
+  const { getTroubleshootSession, createTroubleshootSession, saveTroubleshootSession, deleteTroubleshootSession } = await import('../agents/troubleshoot-agent');
 
   if (action === 'cancel') {
-    await deleteTroubleshootSession(env.SESSION_KV, telegramUserId);
+    await deleteTroubleshootSession(env.DB, telegramUserId);
     return '✅ 트러블슈팅 세션이 취소되었습니다.';
   }
 
   // action === 'start'
-  const existingSession = await getTroubleshootSession(env.SESSION_KV, telegramUserId);
+  const existingSession = await getTroubleshootSession(env.DB, telegramUserId);
 
   if (existingSession && existingSession.status !== 'completed') {
     return '이미 진행 중인 트러블슈팅 세션이 있습니다. 계속 진행해주세요.\n\n현재까지 파악된 정보:\n' +
-      (existingSession.collectedInfo.category ? `• 분류: ${existingSession.collectedInfo.category}\n` : '') +
-      (existingSession.collectedInfo.symptoms ? `• 증상: ${existingSession.collectedInfo.symptoms}\n` : '');
+      (existingSession.collected_info.category ? `• 분류: ${existingSession.collected_info.category}\n` : '') +
+      (existingSession.collected_info.symptoms ? `• 증상: ${existingSession.collected_info.symptoms}\n` : '');
   }
 
   // Create new session
-  const newSession = {
-    telegramUserId,
-    status: 'gathering' as const,
-    collectedInfo: {},
-    messages: [],
-    createdAt: Date.now(),
-    updatedAt: Date.now(),
-  };
+  const newSession = createTroubleshootSession(telegramUserId, 'gathering');
 
-  await saveTroubleshootSession(env.SESSION_KV, telegramUserId, newSession);
+  await saveTroubleshootSession(env.DB, newSession);
 
   logger.info('트러블슈팅 세션 시작', { userId: telegramUserId });