chore(release): bump to 1.2.14 "Just cleaning"

- version: Cargo.toml, tauri.conf.json, package.json (+ Cargo.lock, package-lock.json)
- metainfo.xml: add 1.2.14 release entry
- About modal codename -> "Just cleaning"
- docs/release-1.2.14: TAG_DETAILS.md + CHANGELOG_FULL.md

Snap and Nix flake are intentionally left at 1.2.13: they pin a source
tag, and this is a no-tag, build-only cycle (no distribution).

cc

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "QBZ",
-  "version": "1.2.13",
+  "version": "1.2.14",
   "identifier": "com.blitzfc.qbz",
   "build": {
     "beforeDevCommand": "npm run dev",