refactor: Migrate to API v2

- Added auto schema migration
- Refactored /api/subs, /api/collections, /api/artifacts. Now these APIs will return array instead of object. This enables sorting items in the future.

backend/jsconfig.json

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["src/*"]
+    }
+  }
+}