Initial commit: AI-driven visual novel scaffold

- Monorepo (pnpm workspace): apps/web + packages/{types,ai-client,engine}
- Next.js 16 web app with three-stage AI orchestration
- Three independently configurable providers: text LLM, image generator, vision model
- Warm minimalist editorial UI design
- One-click Vercel deploy ready

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/lib/config.ts

@@ -0,0 +1,27 @@
+import type { EngineConfig } from "@dada/types";
+
+function readVar(name: string): string {
+  const v = process.env[name];
+  if (!v) throw new Error(`Missing required environment variable: ${name}`);
+  return v;
+}
+
+export function loadEngineConfig(): EngineConfig {
+  return {
+    text: {
+      baseUrl: readVar("TEXT_BASE_URL"),
+      apiKey: readVar("TEXT_API_KEY"),
+      model: readVar("TEXT_MODEL"),
+    },
+    image: {
+      baseUrl: readVar("IMAGE_BASE_URL"),
+      apiKey: readVar("IMAGE_API_KEY"),
+      model: readVar("IMAGE_MODEL"),
+    },
+    vision: {
+      baseUrl: readVar("VISION_BASE_URL"),
+      apiKey: readVar("VISION_API_KEY"),
+      model: readVar("VISION_MODEL"),
+    },
+  };
+}