0.3.8 — plugins install from the catalog only (no auto-install)

Drop first-run auto-install. New plugins are discovered and installed by hand
from Settings → Plugins, which now shows an 'Available to install' catalog
fetched from the Gitea plugin registry (with loading / offline-retry states).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "exbyte-depot",
   "private": true,
-  "version": "0.3.7",
+  "version": "0.3.8",
   "type": "module",
   "scripts": {
     "dev": "vite",