fix: 代码审查 P0+P1 问题修复（2 个崩溃 + 14 个体验问题）

P0 致命问题：
- LivePhotoCore: requestLivePhoto continuation 多次 resume 崩溃
  使用 ResumeOnce + highQualityFormat + 跳过降级版本
- ResultView: PHLivePhoto.request continuation 泄漏/多次 resume
  NSLock + hasResumed 守卫 + 处理 cancel/error 边缘情况

P1 并发安全：
- PresetManager/RecentWorksManager: 移除 NotificationCenter 闭包
  中的 guard let self（Swift 6 并发安全）
- RecentWorksManager: cleanupDeletedAssets 移到 Task.detached
- RecentWorksManager: ThumbnailLoader.load 移到后台 + 防重复

P1 EditorView 修复：
- AI 百分比改用 .percent FormatStyle（本地化）
- 预设选择器 if-else 互斥 + Group 包裹
- 诊断按钮优先使用 suggestion.action 闭包
- PhotosPicker 导入添加 50MB 大小限制
- 封面文件写入 try? 改为 do-catch

P1 其他修复：
- HomeView: selectedItem 在所有退出路径重置
- LivePhotoCore: trimmedSeconds 改用实际裁剪后视频时长
- LivePhotoCore: keyFrameTime 越界显式 clamp + DEBUG 警告
- LivePhotoCore: ExportParams Codable 向后兼容

本地化：
- Localizable.xcstrings 9 批翻译修复（~295 条）
  ar/es/fr/ja/ko 英文占位替换为正确翻译

修改文件：
- Sources/LivePhotoCore/LivePhotoCore.swift
- to-live-photo/Views/ResultView.swift
- to-live-photo/Views/HomeView.swift
- to-live-photo/Views/EditorView.swift
- to-live-photo/PresetManager.swift
- to-live-photo/RecentWorksManager.swift
- to-live-photo/Localizable.xcstrings

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Sources/LivePhotoCore/LivePhotoCore.swift

@@ -177,6 +177,25 @@ public struct ExportParams: Codable, Sendable, Hashable {
         params.hdrPolicy = .toneMapToSDR
         return params
     }
+
+    // MARK: - Codable 向后兼容
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        trimStart = try container.decode(Double.self, forKey: .trimStart)
+        trimEnd = try container.decode(Double.self, forKey: .trimEnd)
+        keyFrameTime = try container.decode(Double.self, forKey: .keyFrameTime)
+        audioPolicy = try container.decode(AudioPolicy.self, forKey: .audioPolicy)
+        codecPolicy = try container.decode(CodecPolicy.self, forKey: .codecPolicy)
+        hdrPolicy = try container.decode(HDRPolicy.self, forKey: .hdrPolicy)
+        maxDimension = try container.decode(Int.self, forKey: .maxDimension)
+        cropRect = try container.decode(CropRect.self, forKey: .cropRect)
+        aspectRatio = try container.decode(AspectRatioTemplate.self, forKey: .aspectRatio)
+        compatibilityMode = try container.decode(Bool.self, forKey: .compatibilityMode)
+        targetFrameRate = try container.decode(Int.self, forKey: .targetFrameRate)
+        coverImageURL = try container.decodeIfPresent(URL.self, forKey: .coverImageURL)
+        aiEnhanceConfig = try container.decodeIfPresent(AIEnhanceConfig.self, forKey: .aiEnhanceConfig) ?? .disabled
+    }
 }
 
 public struct AppError: Error, Codable, Sendable, Hashable {
@@ -399,13 +418,22 @@ public actor LivePhotoValidator {
         }
 
         return await withCheckedContinuation { continuation in
+            let resumeOnce = ResumeOnce()
+            let options = PHLivePhotoRequestOptions()
+            options.deliveryMode = .highQualityFormat
             PHImageManager.default().requestLivePhoto(
                 for: asset,
                 targetSize: CGSize(width: 1, height: 1),
                 contentMode: .aspectFit,
-                options: nil
-            ) { livePhoto, _ in
-                continuation.resume(returning: livePhoto)
+                options: options
+            ) { livePhoto, info in
+                // 跳过降级版本，等待完整版本
+                if let isDegraded = info?[PHImageResultIsDegradedKey] as? Bool, isDegraded {
+                    return
+                }
+                if resumeOnce.tryConsume() {
+                    continuation.resume(returning: livePhoto)
+                }
             }
         }
     }
@@ -521,8 +549,10 @@ public actor LivePhotoBuilder {
                 destinationURL: trimmedURL
             )
 
-            // 根据用户选择的裁剪时长动态计算目标时长（上限 5 秒）
-            let trimmedSeconds = min(max(exportParams.trimEnd - exportParams.trimStart, 0.5), 5.0)
+            // 从实际裁剪后的视频读取真实时长，避免 trimEnd 超过视频实际时长导致偏差
+            let trimmedAsset = AVURLAsset(url: trimmedVideoURL)
+            let actualTrimmedDuration = try await trimmedAsset.load(.duration).seconds
+            let trimmedSeconds = min(max(actualTrimmedDuration, 0.5), 5.0)
             let targetDuration = CMTime(seconds: trimmedSeconds, preferredTimescale: 600)
             progress?(LivePhotoBuildProgress(stage: .normalize, fraction: 0.5))
             let scaledVideoURL = try await scaleVideoToTargetDuration(
@@ -535,8 +565,19 @@ public actor LivePhotoBuilder {
                 destinationURL: scaledURL
             )
 
+            // 显式 clamp keyFrameTime 到 [trimStart, trimEnd] 范围
+            let clampedKeyFrameTime: Double
+            if exportParams.keyFrameTime < exportParams.trimStart || exportParams.keyFrameTime > exportParams.trimEnd {
+                #if DEBUG
+                print("[LivePhotoBuilder] WARNING: keyFrameTime \(exportParams.keyFrameTime) out of range [\(exportParams.trimStart), \(exportParams.trimEnd)], clamping")
+                #endif
+                clampedKeyFrameTime = min(max(exportParams.keyFrameTime, exportParams.trimStart), exportParams.trimEnd)
+            } else {
+                clampedKeyFrameTime = exportParams.keyFrameTime
+            }
+
             // 计算关键帧在目标视频中的绝对时间位置
-            let keyFrameRatio = (exportParams.keyFrameTime - exportParams.trimStart) / max(0.001, exportParams.trimEnd - exportParams.trimStart)
+            let keyFrameRatio = (clampedKeyFrameTime - exportParams.trimStart) / max(0.001, exportParams.trimEnd - exportParams.trimStart)
             let relativeKeyFrameTime = max(0, min(trimmedSeconds, keyFrameRatio * trimmedSeconds))
 
             progress?(LivePhotoBuildProgress(stage: .extractKeyFrame, fraction: 0))