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/types.ts

@@ -320,3 +320,31 @@ export interface DomainRegisterKeyboardData {
 }
 
 export type KeyboardData = DomainRegisterKeyboardData;
+
+// Workers AI Types (from worker-configuration.d.ts)
+export type WorkersAIModel =
+  | '@cf/meta/llama-3.1-8b-instruct'
+  | '@cf/meta/llama-3.2-3b-instruct'
+  | '@cf/meta/llama-3-8b-instruct';
+
+export interface WorkersAIMessage {
+  role: 'system' | 'user' | 'assistant';
+  content: string;
+}
+
+export interface WorkersAITextGenerationInput {
+  prompt?: string;
+  messages?: WorkersAIMessage[];
+  max_tokens?: number;
+  temperature?: number;
+  stream?: boolean;
+}
+
+export interface WorkersAITextGenerationOutput {
+  response?: string;
+  usage?: {
+    prompt_tokens: number;
+    completion_tokens: number;
+    total_tokens: number;
+  };
+}