feat: migrate on-device Qwen3 ASR to CoreML for background Flow dictation

Replace MLX GPU inference with CoreML bundles so transcription continues
while the host app is backgrounded. Adds model download and warm-up,
vendored Qwen3Speech, and updates onboarding, settings, and copy for the
~1.6 GB CoreML package (iOS 18+).

OSGKeyboardShared/Models/EngineServiceLabel.swift

@@ -9,18 +9,37 @@ public enum EngineServiceLabel {
     public static func summary(
         engineMode: String,
         providerId: String,
-        model: String
+        model: String,
+        localASRBackend: LocalASRBackend = .speechAnalyzer,
+        language: AppUILanguage? = nil
     ) -> String {
-        let isChinese = Locale.preferredLanguages.first?.hasPrefix("zh") == true
-        let prefix = isChinese ? "当前：" : "Active: "
+        let lang = language ?? AppGroupStore().uiLanguage
         if engineMode == "local" {
-            return isChinese
-                ? "\(prefix)本地引擎 · Apple SpeechAnalyzer"
-                : "\(prefix)On-device · Apple SpeechAnalyzer"
+            let asrName = asrDisplayName(for: localASRBackend, language: lang)
+            return SharedL10n.format("engine.summary.local", language: lang, asrName)
         }
-        let providerName = ProviderDisplayName.name(for: providerId)
+        let providerName = ProviderDisplayName.name(for: providerId, language: lang)
         let trimmedModel = model.trimmingCharacters(in: .whitespacesAndNewlines)
-        if trimmedModel.isEmpty { return "\(prefix)\(providerName)" }
-        return "\(prefix)\(providerName) · \(trimmedModel)"
+        if trimmedModel.isEmpty {
+            return SharedL10n.format("engine.summary.cloud", language: lang, providerName)
+        }
+        return SharedL10n.format(
+            "engine.summary.cloudWithModel",
+            language: lang,
+            providerName,
+            trimmedModel
+        )
+    }
+
+    private static func asrDisplayName(
+        for backend: LocalASRBackend,
+        language: AppUILanguage
+    ) -> String {
+        switch backend {
+        case .speechAnalyzer:
+            return SharedL10n.string("engine.asr.appleSpeech", language: language)
+        case .qwen3ASR:
+            return SharedL10n.string("model.qwen3asr.name", language: language)
+        }
     }
 }