refactor: remove Workers AI as any with proper type definitions

- Add WorkersAIModel, WorkersAITextGenerationInput/Output types
- Remove `as any` from summary-service.ts (4 instances)
- Remove `as any` from bank-sms-parser.ts (3 instances)
- Remove `as any` from n8n-service.ts (2 instances)
- Add OpenAIResponse interface for API responses

Type-safe Workers AI calls with full IntelliSense support.

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

src/summary-service.ts

@@ -1,4 +1,4 @@
-import { Env, BufferedMessage, Summary, ConversationContext } from './types';
+import { Env, BufferedMessage, Summary, ConversationContext, WorkersAITextGenerationOutput, WorkersAITextGenerationInput } from './types';
 import { createLogger } from './utils/logger';
 
 const logger = createLogger('summary-service');
@@ -190,10 +190,14 @@ ${userMessages}
   }
 
   // 폴백: Workers AI
-  const response = await env.AI.run('@cf/meta/llama-3.1-8b-instruct' as any, {
+  const input: WorkersAITextGenerationInput = {
     messages: [{ role: 'user', content: prompt }],
     max_tokens: 500,
-  }) as any;
+  };
+  const response = await env.AI.run(
+    '@cf/meta/llama-3.1-8b-instruct' as '@cf/meta/llama-3.1-8b-instruct-fp8',
+    input
+  ) as WorkersAITextGenerationOutput;
 
   return response.response || '프로필 생성 실패';
 }
@@ -329,14 +333,18 @@ ${integratedProfile}
   }
 
   // 폴백: Workers AI
-  const response = await env.AI.run('@cf/meta/llama-3.1-8b-instruct' as any, {
+  const input: WorkersAITextGenerationInput = {
     messages: [
       { role: 'system', content: systemPrompt },
       ...recentContext,
       { role: 'user', content: userMessage },
     ],
     max_tokens: 500,
-  }) as any;
+  };
+  const response = await env.AI.run(
+    '@cf/meta/llama-3.1-8b-instruct' as '@cf/meta/llama-3.1-8b-instruct-fp8',
+    input
+  ) as WorkersAITextGenerationOutput;
 
   return response.response || '응답을 생성할 수 없습니다.';
 }