feat(languages): add Slovenian (sl) to the supported languages (#995)

Slovenian was missing from SUPPORTED_LANGUAGES, so the Settings picker did not offer it and normalize_language_shortcuts dropped any shortcut bound to it. Add it as a Whisper-only entry (whisper code sl; alphacephei publishes no Slovenian VOSK model), map the Slovenian XKB layout si to it for follow-keyboard-layout, and list it on the website languages page.

Fixes #970

web/src/app/languages/page.tsx

@@ -216,6 +216,14 @@ const supportedLanguages = [
     description: "Russian language speech-to-text transcription",
     engines: [...ALL_ENGINES],
   },
+  {
+    code: "sl",
+    name: "Slovenian",
+    nativeName: "Slovenščina",
+    flag: "🇸🇮",
+    description: "Slovenian dictation with multilingual Whisper models",
+    engines: [...WHISPER_ENGINES],
+  },
   {
     code: "es",
     name: "Spanish",
@@ -314,6 +322,7 @@ export const metadata: Metadata = buildPageMetadata({
     "Italian voice recognition",
     "Portuguese voice typing",
     "Russian speech recognition",
+    "Slovenian voice typing",
     "Chinese dictation",
     "Hindi voice typing",
     "Linux multilingual dictation",