chore(release): bump version to 1.2.13 "400+ stars"

Version bumped across Cargo.toml, tauri.conf.json, package.json, snapcraft.yaml (version + source-tag), flake.nix, and the lockfiles. metainfo.xml gains a 1.2.13 release entry, the About modal codename becomes "400+ stars", and the README contributors list adds @Vudgekek and @DoubleGate.

cc

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "qbz-nix"
-version = "1.2.12"
+version = "1.2.13"
 description = "Native high-fidelity client for Qobuz™ subscribers on Linux with Hi-Fi audio support (uses the Qobuz API; not certified by Qobuz)"
 authors = ["blitzkriegfc"]
 edition = "2021"