feat(macos): local ASR model manager, menu-bar polish, and release 0.5.2

Adds a bundled local ASR model catalog for the macOS app with one-click
Sherpa Qwen3 / SenseVoice downloads (pause/resume, inline actions) and a
shared model storage directory used by MLX Qwen3. Fixes the light-mode
sidebar material and makes the menu-bar icon follow the system appearance
with a refreshed status mark. Renames the built product to OSGKeyboard.app.

Bumps version to 0.5.2 (build 19).

OSGKeyboardShared/Services/PolishingService.swift

@@ -252,7 +252,10 @@ public actor PolishingService {
         providerId: String
     ) -> String {
         let dictionary = store.personalDictionary
-        let dictionaryBlock = dictionary.promptFragment()
+        let dictionaryBlock = Self.mergedDictionaryBlock(
+            dictionary: dictionary,
+            supplement: context.dictionarySupplement
+        )
         let contextGuideline = context.appContext.polishGuideline
         let intensityGuideline = context.intensity.promptGuideline
         let contract = Self.globalOutputContract(useChinese: shouldUseChineseGuidance(providerId: providerId))
@@ -321,6 +324,17 @@ public actor PolishingService {
         }
     }
 
+    internal static func mergedDictionaryBlock(
+        dictionary: PersonalDictionary,
+        supplement: String?
+    ) -> String {
+        let base = dictionary.promptFragment()
+        let extra = supplement?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
+        if base.isEmpty { return extra }
+        if extra.isEmpty { return base }
+        return base + "\n" + extra
+    }
+
     private func shouldUseChineseGuidance(providerId: String) -> Bool {
         switch providerId {
         case "zhipu", "moonshot", "qwen", "deepseek":