refactor: 簡化選項詞彙庫資料模型設計

移除不必要的欄位以降低維護成本和實作複雜度：
- 移除 FrequencyRating（頻率評級）
- 移除 ChineseTranslation（中文翻譯）
- 移除 Synonyms（同義詞列表）
- 移除 Source（詞彙來源）
- 移除 QualityScore（品質評分）

保留核心三參數匹配功能：CEFR等級、詞性、字數
專注於解決測驗選項生成的核心需求

🤖 Generated with [Claude Code](https://claude.ai/code)

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

選項詞彙庫功能規格書.md

@@ -36,10 +36,10 @@
 | REQ-002 | 根據字數（字元長度）匹配類似長度的詞彙 | 高 |
 | REQ-003 | 根據詞性匹配相同詞性的詞彙 | 高 |
 | REQ-004 | 每次生成 3 個不同的干擾項 | 高 |
-| REQ-005 | 避免選擇同義詞作為干擾項 | 中 |
+| REQ-005 | 支援多種測驗類型（詞彙選擇、聽力等） | 中 |
-| REQ-006 | 避免選擇拼寫過於相似的詞彙 | 中 |
+| REQ-006 | 提供詞彙庫管理介面 | 低 |
-| REQ-007 | 支援多種測驗類型（詞彙選擇、聽力等） | 中 |
+
-| REQ-008 | 提供詞彙庫管理介面 | 低 |
+> **設計簡化說明**：為降低維護成本和實作複雜度，移除了同義詞排除、品質評分、頻率評級等進階功能。專注於三參數匹配的核心功能，確保系統簡潔實用。
 
 ### 非功能需求
 | 需求ID | 描述 | 指標 |
@@ -112,46 +112,16 @@ public class OptionsVocabulary
     public string PartOfSpeech { get; set; } = string.Empty;
 
     /// <summary>
-    /// 字數（字元長度）
+    /// 字數（字元長度）- 自動從 Word 計算
     /// </summary>
     [Index("IX_OptionsVocabulary_WordLength")]
     public int WordLength { get; set; }
 
-    /// <summary>
-    /// 詞彙使用頻率（1-5，5最高）
-    /// </summary>
-    [Range(1, 5)]
-    public int FrequencyRating { get; set; } = 3;
-
-    /// <summary>
-    /// 中文翻譯（用於避免同義詞）
-    /// </summary>
-    [MaxLength(200)]
-    public string? ChineseTranslation { get; set; }
-
-    /// <summary>
-    /// 同義詞列表（JSON 格式，用於排除）
-    /// </summary>
-    [MaxLength(500)]
-    public string? Synonyms { get; set; }
-
-    /// <summary>
-    /// 詞彙來源（dictionary, corpus, manual）
-    /// </summary>
-    [MaxLength(50)]
-    public string? Source { get; set; }
-
     /// <summary>
     /// 是否啟用
     /// </summary>
     public bool IsActive { get; set; } = true;
 
-    /// <summary>
-    /// 品質評分（用於優先排序）
-    /// </summary>
-    [Range(0, 100)]
-    public int QualityScore { get; set; } = 50;
-
     /// <summary>
     /// 創建時間
     /// </summary>
@@ -176,8 +146,8 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 
     // 啟用狀態索引
     modelBuilder.Entity<OptionsVocabulary>()
-        .HasIndex(e => new { e.IsActive, e.QualityScore })
+        .HasIndex(e => e.IsActive)
-        .HasDatabaseName("IX_OptionsVocabulary_Active_Quality");
+        .HasDatabaseName("IX_OptionsVocabulary_Active");
 }
 ```
 
@@ -253,13 +223,9 @@ public class DistractorGenerationService
         var maxLength = targetLength + 2;
         baseQuery = baseQuery.Where(v => v.WordLength >= minLength && v.WordLength <= maxLength);
 
-        // 5. 排除同義詞（如果有定義）
+        // 5. 隨機排序選取候選詞
-        // TODO: 實現同義詞排除邏輯
-
-        // 6. 按品質評分和隨機性排序
         var candidates = await baseQuery
-            .OrderByDescending(v => v.QualityScore)
+            .OrderBy(v => Guid.NewGuid())
-            .ThenBy(v => Guid.NewGuid())
             .Take(10) // 取更多候選詞再篩選
             .Select(v => v.Word)
             .ToListAsync();
@@ -357,10 +323,7 @@ public class OptionsVocabularyController : ControllerBase
             Word = request.Word,
             CEFRLevel = request.CEFRLevel,
             PartOfSpeech = request.PartOfSpeech,
-            WordLength = request.Word.Length,
+            WordLength = request.Word.Length
-            FrequencyRating = request.FrequencyRating,
-            ChineseTranslation = request.ChineseTranslation,
-            Source = "manual"
         };
 
         var success = await _vocabularyService.AddVocabularyAsync(vocabulary);
@@ -378,10 +341,7 @@ public class OptionsVocabularyController : ControllerBase
             Word = r.Word,
             CEFRLevel = r.CEFRLevel,
             PartOfSpeech = r.PartOfSpeech,
-            WordLength = r.Word.Length,
+            WordLength = r.Word.Length
-            FrequencyRating = r.FrequencyRating,
-            ChineseTranslation = r.ChineseTranslation,
-            Source = "bulk-import"
         }).ToList();
 
         var importedCount = await _vocabularyService.BulkImportAsync(vocabularies);
@@ -442,14 +402,6 @@ public class AddVocabularyRequest
     [MaxLength(20)]
     public string PartOfSpeech { get; set; } = string.Empty;
 
-    [Range(1, 5)]
-    public int FrequencyRating { get; set; } = 3;
-
-    [MaxLength(200)]
-    public string? ChineseTranslation { get; set; }
-
-    [MaxLength(500)]
-    public string? Synonyms { get; set; }
 }
 ```
 
@@ -472,12 +424,7 @@ public partial class AddOptionsVocabularyTable : Migration
                 CEFRLevel = table.Column<string>(maxLength: 2, nullable: false),
                 PartOfSpeech = table.Column<string>(maxLength: 20, nullable: false),
                 WordLength = table.Column<int>(nullable: false),
-                FrequencyRating = table.Column<int>(nullable: false, defaultValue: 3),
-                ChineseTranslation = table.Column<string>(maxLength: 200, nullable: true),
-                Synonyms = table.Column<string>(maxLength: 500, nullable: true),
-                Source = table.Column<string>(maxLength: 50, nullable: true),
                 IsActive = table.Column<bool>(nullable: false, defaultValue: true),
-                QualityScore = table.Column<int>(nullable: false, defaultValue: 50),
                 CreatedAt = table.Column<DateTime>(nullable: false),
                 UpdatedAt = table.Column<DateTime>(nullable: false)
             },
@@ -499,9 +446,9 @@ public partial class AddOptionsVocabularyTable : Migration
             columns: new[] { "CEFRLevel", "PartOfSpeech", "WordLength" });
 
         migrationBuilder.CreateIndex(
-            name: "IX_OptionsVocabulary_Active_Quality",
+            name: "IX_OptionsVocabulary_Active",
             table: "OptionsVocabularies",
-            columns: new[] { "IsActive", "QualityScore" });
+            column: "IsActive");
     }
 
     protected override void Down(MigrationBuilder migrationBuilder)
@@ -619,19 +566,19 @@ public class VocabularySeeder
         var vocabularies = new List<OptionsVocabulary>
         {
             // A1 Level - 名詞
-            new() { Word = "cat", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 3, FrequencyRating = 5, ChineseTranslation = "貓" },
+            new() { Word = "cat", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 3 },
-            new() { Word = "dog", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 3, FrequencyRating = 5, ChineseTranslation = "狗" },
+            new() { Word = "dog", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 3 },
-            new() { Word = "book", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 4, FrequencyRating = 5, ChineseTranslation = "書" },
+            new() { Word = "book", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 4 },
 
             // A1 Level - 動詞
-            new() { Word = "eat", CEFRLevel = "A1", PartOfSpeech = "verb", WordLength = 3, FrequencyRating = 5, ChineseTranslation = "吃" },
+            new() { Word = "eat", CEFRLevel = "A1", PartOfSpeech = "verb", WordLength = 3 },
-            new() { Word = "run", CEFRLevel = "A1", PartOfSpeech = "verb", WordLength = 3, FrequencyRating = 4, ChineseTranslation = "跑" },
+            new() { Word = "run", CEFRLevel = "A1", PartOfSpeech = "verb", WordLength = 3 },
-            new() { Word = "walk", CEFRLevel = "A1", PartOfSpeech = "verb", WordLength = 4, FrequencyRating = 5, ChineseTranslation = "走" },
+            new() { Word = "walk", CEFRLevel = "A1", PartOfSpeech = "verb", WordLength = 4 },
 
             // B1 Level - 形容詞
-            new() { Word = "beautiful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9, FrequencyRating = 4, ChineseTranslation = "美麗的" },
+            new() { Word = "beautiful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9 },
-            new() { Word = "wonderful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9, FrequencyRating = 4, ChineseTranslation = "精彩的" },
+            new() { Word = "wonderful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9 },
-            new() { Word = "excellent", CEFRLevel = "B2", PartOfSpeech = "adjective", WordLength = 9, FrequencyRating = 4, ChineseTranslation = "優秀的" },
+            new() { Word = "excellent", CEFRLevel = "B2", PartOfSpeech = "adjective", WordLength = 9 },
 
             // ... 更多詞彙
         };