feat(Me): 推理引擎切换页 + SME2 状态 + CLAUDE.md 更新(Phase 5 部分)

- InferenceSettingsView:MNN(CPU/SME2)/ MLX(GPU)单选切换,展示当前设备
  SME2 探测状态(A19 启用 / A17 回退);走设计系统卡片,新文件不动 WIP 的
  ModelManagementView
- MeView:「模型管理」下新增「推理引擎」入口,detail 显示 MNN·SME2 / MNN·CPU / MLX·GPU
- CLAUDE.md §2/§12:AI 运行时改为 MNN(主,SME2)+ MLX(兜底)双后端,
  卖点 #2 明确 MNN+Arm SME2 端侧 CPU 加速为挑战赛考核点

模拟器 BUILD SUCCEEDED,0 error。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

康康/Features/Me/MeView.swift

@@ -37,6 +37,7 @@ struct MeView: View {
                     profileCard
                     customMetricsCard
                     modelManagementCard
+                    inferenceEngineCard
                     languageCard
                     fontScaleCard
                     faceIDCard
@@ -157,6 +158,22 @@ struct MeView: View {
         return readyCount == 0 ? String(appLoc: "未下载") : String(appLoc: "\(readyCount)/\(ModelKind.allCases.count) 就绪")
     }
 
+    private var inferenceEngineCard: some View {
+        NavigationLink {
+            InferenceSettingsView()
+        } label: {
+            settingsCard(title: String(appLoc: "推理引擎"), detail: engineDetail, icon: "cpu.fill")
+        }
+        .buttonStyle(.plain)
+    }
+
+    private var engineDetail: String {
+        switch InferenceEngine.current {
+        case .mnn: return InferenceEngine.cpuSupportsSME2 ? "MNN · SME2" : "MNN · CPU"
+        case .mlx: return "MLX · GPU"
+        }
+    }
+
     private var languageCard: some View {
         NavigationLink {
             LanguageSettingsView()