Fix Docker build failure: lazy-initialize MinIO client

The production env var check in createMinioClient() was throwing during
`next build` page data collection because MINIO_ACCESS_KEY/SECRET_KEY
aren't available at Docker build time. Changed from eager module-level
initialization to a lazy Proxy pattern that defers client creation to
first actual use, while maintaining backward compatibility with all
existing `minio.method()` call sites.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/minio.ts

@@ -1,6 +1,6 @@
 import * as Minio from 'minio'
 
-// MinIO client singleton
+// MinIO client singleton (lazy-initialized to avoid build-time errors)
 const globalForMinio = globalThis as unknown as {
   minio: Minio.Client | undefined
 }
@@ -30,9 +30,24 @@ function createMinioClient(): Minio.Client {
   })
 }
 
-export const minio = globalForMinio.minio ?? createMinioClient()
+/**
+ * Get the MinIO client instance (lazy-initialized).
+ * The client is only created on first access, not at module import time.
+ * This prevents build-time errors when env vars are not available.
+ */
+export function getMinioClient(): Minio.Client {
+  if (!globalForMinio.minio) {
+    globalForMinio.minio = createMinioClient()
+  }
+  return globalForMinio.minio
+}
 
-if (process.env.NODE_ENV !== 'production') globalForMinio.minio = minio
+// Backward-compatible export — lazy getter via Proxy
+export const minio: Minio.Client = new Proxy({} as Minio.Client, {
+  get(_target, prop, receiver) {
+    return Reflect.get(getMinioClient(), prop, receiver)
+  },
+})
 
 // Default bucket name
 export const BUCKET_NAME = process.env.MINIO_BUCKET || 'mopc-files'