feat: macOS architecture, cloud ASR/LLM providers, and 6-step iOS onboarding

- Add macOS menu-bar dictation app with local ASR models (SenseVoice/Qwen3),
  global Option hotkey, and bottom overlay
- Add cloud ASR/LLM providers (Anthropic, Volcengine, Bailian, and more) with
  provider logos, model listing, and connection checks
- Add shared 7-day usage stats UI (UsageStatsCluster / SevenDayUsageChart)
- Add iOS onboarding step 6 for polish LLM setup; hide custom-language-model
  diagnostic toggle behind DEBUG
- Unify iOS onboarding tagline with the macOS brand line ("开口即文字。")
- Rewrite README (Chinese-first, product-oriented) and refresh GitHub Pages

OSGKeyboardTests/ConfigurationStoreTests.swift

@@ -62,9 +62,9 @@ final class ConfigurationStoreTests: XCTestCase {
         XCTAssertTrue(asrClient is ZhipuCloudASRClient)
     }
 
-    func testLegacyInstallCopiesProviderIdToAsrProviderId() {
+    func testLegacyInstallCopiesProviderIdToAsrProviderIdThenMigratesQwen() {
         defaults.set("qwen", forKey: AppGroupConfiguration.Keys.providerId)
         let config = AppGroupConfiguration.load(fromAvailable: defaults)
-        XCTAssertEqual(config.asrProviderId, "qwen")
+        XCTAssertEqual(config.asrProviderId, "bailian")
     }
 }