i18n: complete Slovak Monitor and CLI messages

AppImage/lib/api-errors.ts

@@ -0,0 +1,17 @@
+import enMessages from "../messages/en/common.json"
+import skMessages from "../messages/sk/common.json"
+import { detectBrowserLanguage, LANGUAGE_STORAGE_KEY } from "./i18n/languages"
+
+type Failure = keyof typeof enMessages.apiErrors
+
+// fetchApi also runs outside React hooks. Read the provider's current document
+// language, with its stored/browser preference as a fallback.
+export function apiFailure(key: Failure, params: Record<string, string | number> = {}): string {
+  let language = typeof document === "undefined" ? "" : document.documentElement?.lang
+  if (!language && typeof window !== "undefined") {
+    try { language = window.localStorage.getItem(LANGUAGE_STORAGE_KEY) || "" } catch { /* private browsing */ }
+  }
+  language ||= detectBrowserLanguage()
+  const messages = language === "sk" ? skMessages.apiErrors : enMessages.apiErrors
+  return messages[key].replace(/\{(\w+)\}/g, (match, name) => params[name] === undefined ? match : String(params[name]))
+}