chore: bump version to 1.2.1

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

cc

package.json

@@ -1,6 +1,6 @@
 {
   "name": "qbz-nix",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "description": "Native high-fidelity client for Qobuz™ subscribers on Linux with Hi-Fi audio support (uses the Qobuz API; not certified by Qobuz)",
   "type": "module",
   "scripts": {