fix: 完全修復快取資料結構不一致問題和互動式單字查詢功能

- 修復快取API回應中sentenceMeaning大小寫不一致問題
- 完善ClickableTextV2組件對快取資料的屬性讀取相容性
- 新增前端快取狀態顯示（💾 快取結果 / 🤖 AI 分析）
- 統一JSON序列化設定，使用camelCase命名策略
- 新增getWordProperty輔助函數，支援大小寫屬性名稱
- 修復單字彈窗中所有屬性的讀取邏輯
- 完善語法修正和詞彙分析的資料格式相容性
- 新增詳細的系統功能分析文檔

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

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

backend/DramaLing.Api/Controllers/AIController.cs

@@ -536,8 +536,15 @@ public class AIController : ControllerBase
             {
                 _logger.LogInformation("Using cached analysis for text hash: {TextHash}", cachedAnalysis.InputTextHash);
 
-                // 解析快取的分析結果
-                var cachedResult = System.Text.Json.JsonSerializer.Deserialize<object>(cachedAnalysis.AnalysisResult);
+                // 解析快取的分析結果 - 使用一致的命名策略
+                _logger.LogInformation("Cache raw JSON: {CacheJson}", cachedAnalysis.AnalysisResult);
+
+                var options = new JsonSerializerOptions
+                {
+                    PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+                };
+                var cachedResult = System.Text.Json.JsonSerializer.Deserialize<object>(cachedAnalysis.AnalysisResult, options);
+                _logger.LogInformation("Cache deserialized result: {CachedResult}", System.Text.Json.JsonSerializer.Serialize(cachedResult, options));
 
                 return Ok(new
                 {

backend/DramaLing.Api/Services/AnalysisCacheService.cs

@@ -75,8 +75,12 @@ public class AnalysisCacheService : IAnalysisCacheService
 
             if (existing != null)
             {
-                // 更新現有快取
-                existing.AnalysisResult = JsonSerializer.Serialize(analysisResult);
+                // 更新現有快取 - 使用一致的命名策略
+                var options = new JsonSerializerOptions
+                {
+                    PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+                };
+                existing.AnalysisResult = JsonSerializer.Serialize(analysisResult, options);
                 existing.ExpiresAt = expiresAt;
                 existing.AccessCount++;
                 existing.LastAccessedAt = DateTime.UtcNow;
@@ -89,7 +93,10 @@ public class AnalysisCacheService : IAnalysisCacheService
                     Id = Guid.NewGuid(),
                     InputTextHash = textHash,
                     InputText = inputText,
-                    AnalysisResult = JsonSerializer.Serialize(analysisResult),
+                    AnalysisResult = JsonSerializer.Serialize(analysisResult, new JsonSerializerOptions
+                    {
+                        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+                    }),
                     CreatedAt = DateTime.UtcNow,
                     ExpiresAt = expiresAt,
                     AccessCount = 1,