fix(metadata): add type:module and update exports to fix ERR_MODULE_NOT_FOUND on Vercel

Convert @objectstack/metadata to "type": "module" to align with @objectstack/core,
@objectstack/runtime, and @objectstack/rest. Updates exports from .mjs/.js to .js/.cjs
pattern to ensure proper ESM resolution in Vercel serverless functions.

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>
Agent-Logs-Url: https://github.com/objectstack-ai/spec/sessions/b01a87bf-6ae6-4372-a353-df7cb055f1ec

Author: Copilot

packages/metadata/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Patch Changes
 
+- Fix ERR_MODULE_NOT_FOUND on Vercel: add `"type": "module"` and update exports to use `.js`/`.cjs` pattern (consistent with @objectstack/core, @objectstack/runtime)
 - @objectstack/spec@3.3.0
 - @objectstack/core@3.3.0
 - @objectstack/types@3.3.0

packages/metadata/package.json

@@ -3,18 +3,19 @@
   "version": "3.3.0",
   "license": "Apache-2.0",
   "description": "Metadata loading, saving, and persistence for ObjectStack",
+  "type": "module",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "exports": {
     ".": {
       "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.js"
+      "import": "./dist/index.js",
+      "require": "./dist/index.cjs"
     },
     "./node": {
       "types": "./dist/node.d.ts",
-      "import": "./dist/node.mjs",
-      "require": "./dist/node.js"
+      "import": "./dist/node.js",
+      "require": "./dist/node.cjs"
     }
   },
   "files": [