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/AppGroupStore.swift

@@ -92,6 +92,7 @@ public struct AppGroupStore: @unchecked Sendable {
                 config.model = openAI.defaultModel
             }
         }
+        AppGroupConfigDarwin.postConfigChanged()
     }
 
     public func setUILanguage(_ language: AppUILanguage) {