```

feat(iOS): 更新MNN后端模型配置优化性能

将MNN主模型从Qwen3.5-4B(~2.64GiB)降级为Qwen3.5-2B(~1.1GiB)，因为4B版本
实测运行过慢，影响用户体验。iPhone17+/SME2设备使用2B模型，保留MLX
兜底方案用于模拟器和备用场景，确保AI推理性能和存储效率的平衡。
```

康康Tests/ModelManifestTests.swift

@@ -13,19 +13,19 @@ struct ModelManifestTests {
     }
 
     @Test func llmTotalBytesMatchesManifest() {
-        #expect(ModelManifest.totalBytes(for: .llm) == 3_061_129_077)
+        #expect(ModelManifest.totalBytes(for: .llm) == 1_749_079_691)
     }
 
     @Test func vlTotalBytesMatchesManifest() {
         #expect(ModelManifest.totalBytes(for: .vl) == 3_109_729_929)
     }
 
-    @Test func mnnHasSevenFunctionalFiles() {
-        #expect(ModelManifest.files(for: .mnnLLM).count == 7)
+    @Test func mnnHasSixFunctionalFiles() {
+        #expect(ModelManifest.files(for: .mnnLLM).count == 6)
     }
 
     @Test func mnnTotalBytesMatchesManifest() {
-        #expect(ModelManifest.totalBytes(for: .mnnLLM) == 2_836_770_850)
+        #expect(ModelManifest.totalBytes(for: .mnnLLM) == 1_185_759_005)
     }
 
     @Test func mnnHasEssentialRuntimeFiles() {
@@ -39,7 +39,7 @@ struct ModelManifestTests {
     @Test func mnnFileURLUsesRepoPath() {
         let file = ModelFile(path: "config.json", bytes: 652)
         let url = ModelManifest.fileURL(for: .mnnLLM, file: file)
-        #expect(url.absoluteString == "https://file.myv0.com/Qwen3.5-4B-MNN/config.json")
+        #expect(url.absoluteString == "https://file.myv0.com/Qwen3.5-2B-MNN/config.json")
     }
 
     @Test func excludesReadmeAndGitattributes() {
@@ -62,8 +62,8 @@ struct ModelManifestTests {
     }
 
     @Test func fileURLIsBaseSlashRepoSlashPath() {
-        let file = ModelFile(path: "config.json", bytes: 3_366)
+        let file = ModelFile(path: "config.json", bytes: 3_113)
         let url = ModelManifest.fileURL(for: .llm, file: file)
-        #expect(url.absoluteString == "https://file.myv0.com/Qwen3.5-4B-4bit/config.json")
+        #expect(url.absoluteString == "https://file.myv0.com/Qwen3.5-2B-4bit/config.json")
     }
 }

康康Tests/QuickRegionRecognitionEngineTests.swift

@@ -1,18 +0,0 @@
-import Testing
-@testable import 康康
-
-struct QuickRegionRecognitionEngineTests {
-
-    @Test func defaultsToAppleVisionOCR() {
-        #expect(QuickRegionRecognitionEngine.defaultValue == .appleVision)
-    }
-
-    @Test func rawValuesAreStableForAppStorage() {
-        #expect(QuickRegionRecognitionEngine.appleVision.rawValue == "appleVision")
-        #expect(QuickRegionRecognitionEngine.qwenVL.rawValue == "qwenVL")
-    }
-
-    @Test func unknownStoredValueFallsBackToDefault() {
-        #expect(QuickRegionRecognitionEngine(storedValue: "missing") == .appleVision)
-    }
-}

康康Tests/RegionImageCropperTests.swift

@@ -3,7 +3,7 @@ import CoreGraphics
 import AVFoundation
 @testable import 康康
 
-/// 异常项快拍的局部裁剪几何。
+/// 指标速记的局部裁剪几何。
 /// 回归用例:屏上「宽而矮」的小框,必须裁出「宽 > 高」的照片 rect。
 /// 旧实现用 `metadataOutputRectConverted`(传感器横向坐标)套到竖屏照片 → x/y 轴对调,
 /// 把宽框裁成竖窄条(2026-05-31 真机 bug)。本组用例钉住正确的纯几何映射。
@@ -113,40 +113,4 @@ final class RegionImageCropperTests: XCTestCase {
             .zero)
     }
 
-    /// Qwen3-VL 对宽而矮的局部小图更容易在 processor 缩放后丢字。
-    /// 进入 VL 前应把短边放大并加白边,但不拉伸内容。
-    func testPrepareForQwenVLUpscalesWideShortCropAndAddsPadding() {
-        let image = solidImage(size: CGSize(width: 320, height: 80))
-
-        let prepared = RegionImageCropper.prepareForQwenVL(image)
-
-        XCTAssertGreaterThanOrEqual(prepared.size.height, 448)
-        XCTAssertGreaterThan(prepared.size.width, 320)
-        XCTAssertEqual(prepared.size.width / prepared.size.height,
-                       4.0,
-                       accuracy: 0.8,
-                       "预处理应大致保留宽条内容比例,只允许白边造成轻微变化")
-    }
-
-    func testPrepareForQwenVLDoesNotEnlargePastLongEdgeLimit() {
-        let image = solidImage(size: CGSize(width: 5000, height: 900))
-
-        let prepared = RegionImageCropper.prepareForQwenVL(image)
-
-        XCTAssertLessThanOrEqual(max(prepared.size.width, prepared.size.height), 2400 + 128)
-    }
-
-    private func solidImage(size: CGSize) -> UIImage {
-        let format = UIGraphicsImageRendererFormat.default()
-        format.scale = 1
-        return UIGraphicsImageRenderer(size: size, format: format).image { ctx in
-            UIColor.white.setFill()
-            ctx.fill(CGRect(origin: .zero, size: size))
-            UIColor.black.setFill()
-            ctx.fill(CGRect(x: size.width * 0.1,
-                            y: size.height * 0.35,
-                            width: size.width * 0.8,
-                            height: size.height * 0.3))
-        }
-    }
 }