chore: bump version to 1.2.1

Update all version endpoints, regenerate lockfiles,
add metainfo release entry and release docs.

cc

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "QBZ",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "identifier": "com.blitzfc.qbz",
   "build": {
     "beforeDevCommand": "npm run dev",