feat(Me): 性能自检卡 — 后端标识 + prefill/decode 实测 + 引擎对比存档

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

康康Tests/BenchmarkStoreTests.swift

@@ -0,0 +1,45 @@
+import Testing
+import Foundation
+@testable import 康康
+
+struct BenchmarkStoreTests {
+
+    /// 每个用例独立 suite,避免 Swift Testing 并行执行时互相清空数据。
+    private func freshDefaults(_ name: String) -> UserDefaults {
+        let suite = "test.kk.benchmark.\(name)"
+        let d = UserDefaults(suiteName: suite)!
+        d.removePersistentDomain(forName: suite)
+        return d
+    }
+
+    @Test func savesAndLoadsPerBackend() {
+        let d = freshDefaults("savesAndLoads")
+        let mnn = BenchmarkResult(backendLabel: "MNN · SME2", promptTokens: 30, genTokens: 80,
+                                  prefillTokensPerSecond: 120, decodeTokensPerSecond: 25,
+                                  totalSeconds: 4.2, date: .now)
+        let mlx = BenchmarkResult(backendLabel: "MLX · GPU", promptTokens: 30, genTokens: 80,
+                                  prefillTokensPerSecond: 300, decodeTokensPerSecond: 40,
+                                  totalSeconds: 2.5, date: .now)
+        BenchmarkService.save(mnn, defaults: d)
+        BenchmarkService.save(mlx, defaults: d)
+        let all = BenchmarkService.load(defaults: d)
+        #expect(all.count == 2)
+        #expect(all["MNN · SME2"]?.decodeTokensPerSecond == 25)
+    }
+
+    @Test func overwritesSameBackend() {
+        let d = freshDefaults("overwrites")
+        let old = BenchmarkResult(backendLabel: "MLX · GPU", promptTokens: 1, genTokens: 1,
+                                  prefillTokensPerSecond: 1, decodeTokensPerSecond: 1,
+                                  totalSeconds: 1, date: .now)
+        var new = old
+        new.decodeTokensPerSecond = 99
+        BenchmarkService.save(old, defaults: d)
+        BenchmarkService.save(new, defaults: d)
+        #expect(BenchmarkService.load(defaults: d)["MLX · GPU"]?.decodeTokensPerSecond == 99)
+    }
+
+    @Test func loadOnEmptyReturnsEmpty() {
+        #expect(BenchmarkService.load(defaults: freshDefaults("loadEmpty")).isEmpty)
+    }
+}