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/lib/components/AboutModal.svelte

@@ -99,7 +99,7 @@
             <span class="label">{$t('about.buildInfo.version')}</span>
             <span class="value">{appVersion}</span>
             <span class="label">{$t('about.buildInfo.codename')}</span>
-            <span class="value codename">400+ stars</span>
+            <span class="value codename">Just cleaning</span>
             <span class="label">{$t('about.buildInfo.license')}</span>
             <span class="value">MIT</span>
             <span class="label">{$t('about.buildInfo.platform')}</span>