feat(release): v2.1.2 — CI green: all 5 workflow fixes + .deb

## CI Fixes
- fix(lint): check:docs-sync — bump docs/openapi.yaml version to 2.1.2 + add [Unreleased] to CHANGELOG
- fix(ci): npm-publish.yml — use 'npm ci --ignore-scripts' to skip prepublishOnly during install, then run prepublish.mjs explicitly with JWT_SECRET; prevents double-build loop that caused all npm CI publishes to fail
- fix(ci): docker-publish.yml — replace two-job digest approach (required ubuntu-24.04-arm, unavailable on public repos) with single-job QEMU-based multi-arch build (linux/amd64 + linux/arm64 on standard ubuntu-latest)
- fix(ci): electron-release.yml — add .deb target to Linux electron-builder, collect .deb files in release-assets step, attach *.deb to GitHub release assets

## Documentation
- fix(docs): README.md language bar — fix 29 broken links (README.<lang>.md → docs/i18n/<lang>/README.md)
- fix(docs): docs/i18n/*/README.md — update back-links to ../../README.md and cross-links between languages
- fix(docs): electron/package.json — add deb target (x64+arm64) to linux build config

docs/i18n/da/README.md

@@ -20,7 +20,7 @@ _Din universelle API-proxy — ét slutpunkt, 36+ udbydere, ingen nedetid. Nu me
 
 </div>
 
-🌐 **Tilgængelig på:** 🇺🇸 [engelsk](README.md) | 🇧🇷 [Português (Brasil)](README.pt-BR.md) | 🇪🇸 [Español](README.es.md) | 🇫🇷 [Français](README.fr.md) | 🇮🇹 [Italiano](README.it.md) | 🇷🇺 [Русский](README.ru.md) | 🇨🇳 [中文 (简体)](README.zh-CN.md) | 🇩🇪 [Tysk](README.de.md) | 🇮🇳 [हिन्दी](README.in.md) | 🇹🇭 [ไทย](README.th.md) | 🇺🇦 [Українська](README.uk-UA.md) | 🇸🇦 [العربية](README.ar.md) | 🇯🇵 [日本語](README.ja.md) | 🇻🇳 [Tiếng Việt](README.vi.md) | 🇧🇬 [Български](README.bg.md) | 🇩🇰 [Dansk](README.da.md) | 🇫🇮 [Suomi](README.fi.md) | 🇮🇱 [engelsk](README.he.md) | 🇭🇺 [Magyar](README.hu.md) | 🇮🇩 [Bahasa Indonesien](README.id.md) | 🇰🇷 [한국어](README.ko.md) | 🇲🇾 [Bahasa Melayu](README.ms.md) | 🇳🇱 [Nederlands](README.nl.md) | 🇳🇴 [norsk](README.no.md) | 🇵🇹 [Português (Portugal)](README.pt.md) | 🇷🇴 [Română](README.ro.md) | 🇵🇱 [Polski](README.pl.md) | 🇸🇰 [Slovenčina](README.sk.md) | 🇸🇪 [Svenska](README.sv.md) | 🇵🇭 [filippinsk](README.phi.md)
+🌐 **Tilgængelig på:** 🇺🇸 [engelsk](../../README.md) | 🇧🇷 [Português (Brasil)](../pt-BR/README.md) | 🇪🇸 [Español](../es/README.md) | 🇫🇷 [Français](../fr/README.md) | 🇮🇹 [Italiano](../it/README.md) | 🇷🇺 [Русский](../ru/README.md) | 🇨🇳 [中文 (简体)](../zh-CN/README.md) | 🇩🇪 [Tysk](../de/README.md) | 🇮🇳 [हिन्दी](../in/README.md) | 🇹🇭 [ไทย](../th/README.md) | 🇺🇦 [Українська](../uk-UA/README.md) | 🇸🇦 [العربية](../ar/README.md) | 🇯🇵 [日本語](../ja/README.md) | 🇻🇳 [Tiếng Việt](../vi/README.md) | 🇧🇬 [Български](../bg/README.md) | 🇩🇰 [Dansk](../da/README.md) | 🇫🇮 [Suomi](../fi/README.md) | 🇮🇱 [engelsk](../he/README.md) | 🇭🇺 [Magyar](../hu/README.md) | 🇮🇩 [Bahasa Indonesien](../id/README.md) | 🇰🇷 [한국어](../ko/README.md) | 🇲🇾 [Bahasa Melayu](../ms/README.md) | 🇳🇱 [Nederlands](../nl/README.md) | 🇳🇴 [norsk](../no/README.md) | 🇵🇹 [Português (Portugal)](../pt/README.md) | 🇷🇴 [Română](../ro/README.md) | 🇵🇱 [Polski](../pl/README.md) | 🇸🇰 [Slovenčina](../sk/README.md) | 🇸🇪 [Svenska](../sv/README.md) | 🇵🇭 [filippinsk](../phi/README.md)
 
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