feat(19-02): extract API types and finalize index.ts

Create api.ts with GenerateRequest, GenerateResponse, LLMGenerateRequest,
LLMGenerateResponse. Move RecentModel to providers.ts. Convert index.ts
to pure re-export hub with no type definitions.

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

src/types/api.ts

@@ -0,0 +1,44 @@
+/**
+ * API Types
+ *
+ * Request and response types for API routes including
+ * image generation and LLM text generation.
+ */
+
+import type { AspectRatio, Resolution, ModelType } from "./models";
+import type { LLMProvider, LLMModelType } from "./providers";
+
+// API Request/Response types for Image Generation
+export interface GenerateRequest {
+  images: string[]; // Now supports multiple images
+  prompt: string;
+  aspectRatio?: AspectRatio;
+  resolution?: Resolution; // Only for Nano Banana Pro
+  model?: ModelType;
+  useGoogleSearch?: boolean; // Only for Nano Banana Pro
+}
+
+export interface GenerateResponse {
+  success: boolean;
+  image?: string;
+  video?: string;
+  videoUrl?: string; // For large videos, return URL directly
+  contentType?: "image" | "video";
+  error?: string;
+}
+
+// API Request/Response types for LLM Text Generation
+export interface LLMGenerateRequest {
+  prompt: string;
+  images?: string[];
+  provider: LLMProvider;
+  model: LLMModelType;
+  temperature?: number;
+  maxTokens?: number;
+}
+
+export interface LLMGenerateResponse {
+  success: boolean;
+  text?: string;
+  error?: string;
+}

src/types/index.ts

@@ -1,53 +1,15 @@
-// Re-export all types from domain files
+/**
+ * Type Index
+ *
+ * Central re-export hub for all application types.
+ * Import from domain files for type definitions.
+ */
+
+// Domain re-exports
 export * from "./annotation";
 export * from "./nodes";
 export * from "./providers";
 export * from "./models";
 export * from "./workflow";
-
-// Import types for use in this file
-import type { ProviderType, LLMProvider, LLMModelType } from "./providers";
-import type { AspectRatio, Resolution, ModelType } from "./models";
-
-// Recently used models tracking
-export interface RecentModel {
-  provider: ProviderType;
-  modelId: string;
-  displayName: string;
-  timestamp: number;
-}
-
-// API Request/Response types for Image Generation
-export interface GenerateRequest {
-  images: string[]; // Now supports multiple images
-  prompt: string;
-  aspectRatio?: AspectRatio;
-  resolution?: Resolution; // Only for Nano Banana Pro
-  model?: ModelType;
-  useGoogleSearch?: boolean; // Only for Nano Banana Pro
-}
-
-export interface GenerateResponse {
-  success: boolean;
-  image?: string;
-  video?: string;
-  videoUrl?: string;  // For large videos, return URL directly
-  contentType?: "image" | "video";
-  error?: string;
-}
-
-// API Request/Response types for LLM Text Generation
-export interface LLMGenerateRequest {
-  prompt: string;
-  images?: string[];
-  provider: LLMProvider;
-  model: LLMModelType;
-  temperature?: number;
-  maxTokens?: number;
-}
-
-export interface LLMGenerateResponse {
-  success: boolean;
-  text?: string;
-  error?: string;
-}
+export * from "./api";
+export * from "./quickstart";

src/types/providers.ts

@@ -37,3 +37,11 @@ export type LLMModelType =
   | "gemini-3-pro-preview"
   | "gpt-4.1-mini"
   | "gpt-4.1-nano";
+
+// Recently used models tracking
+export interface RecentModel {
+  provider: ProviderType;
+  modelId: string;
+  displayName: string;
+  timestamp: number;
+}