feat(storage): storage port and minio adapter with forbid-overwrite semantics

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

packages/storage/test/load-env.ts

@@ -0,0 +1,16 @@
+// packages/storage/test/load-env.ts —— 与 services/api/test/load-env.ts 同约定：
+// Jest 侧唯一 env 来源是仓库根 .env。本包嵌套层级与 api 不同（packages/storage/test
+// vs services/api/test），故向上查找 pnpm-workspace.yaml 定位仓库根，不硬编码层数。
+import { existsSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { config } from 'dotenv';
+
+let dir = __dirname;
+while (!existsSync(join(dir, 'pnpm-workspace.yaml'))) {
+  const parent = dirname(dir);
+  if (parent === dir) {
+    throw new Error('load-env: 未找到 pnpm-workspace.yaml，无法定位仓库根（.env）');
+  }
+  dir = parent;
+}
+config({ path: join(dir, '.env') });