feat(api): upgrade zod to v4 and implement api docs and client generation

src/lib/apiHelpers.ts

@@ -0,0 +1,38 @@
+import { NextAuthRequest } from 'next-auth';
+import { extendZodWithOpenApi } from '@asteasolutions/zod-to-openapi';
+import zod from 'zod/v4';
+import { NextResponse } from 'next/server';
+
+extendZodWithOpenApi(zod);
+
+export function userAuthenticated(req: NextAuthRequest) {
+  if (!req.auth || !req.auth.user || !req.auth.user.id)
+    return {
+      continue: false,
+      response: { success: false, message: 'Not authenticated' },
+      metadata: { status: 401 },
+    } as const;
+  return { continue: true, user: req.auth.user } as const;
+}
+
+export function returnZodTypeCheckedResponse<
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  Schema extends zod.ZodType<any, any, any>,
+>(
+  expectedType: Schema,
+  response: zod.input<Schema>,
+  metadata?: { status: number },
+): NextResponse {
+  const result = expectedType.safeParse(response);
+  if (!result.success) {
+    return NextResponse.json(
+      {
+        success: false,
+        message: 'Invalid response format',
+        errors: result.error.issues,
+      },
+      { status: 500 },
+    );
+  }
+  return NextResponse.json(result.data, { status: metadata?.status || 200 });
+}