[Phase2-1.4c] Engine 整合雙軌 GroupBy + fallback 機制

[cct08311github]

Parent Epic

#90

依賴

• [Phase2-1.4a] IGroupByStrategy 介面 + GroupByStrategyResolver #94 (1.4a 介面)
• [Phase2-1.4b] ServerSideGroupByStrategy 實作 (MSSQL 整合測試) #95 (1.4b ServerSide 實作)

任務

將雙軌策略整合進 AnalysisQueryEngine，支援 server-side 優先 + in-process fallback。

實作

修改 src/WalkingTec.Mvvm.Core/Analysis/AnalysisQueryEngine.cs：

public class AnalysisQueryEngine
{
    private readonly GroupByStrategyResolver _resolver;
    
    // 新建構子（DI 友善）
    public AnalysisQueryEngine(GroupByStrategyResolver resolver)
        => _resolver = resolver;
    
    // 保留無參數建構子（向後相容，預設 InProcess）
    public AnalysisQueryEngine()
        => _resolver = GroupByStrategyResolver.Default;
    
    public AnalysisQueryResponse Execute<TModel>(
        IQueryable<TModel> baseQuery,
        AnalysisQueryRequest req,
        IEnumerable<AnalysisFieldMeta> whitelist,
        DBTypeEnum dbType = DBTypeEnum.SQLite)  // 新參數，預設 SQLite（向後相容）
    {
        var strategy = _resolver.Resolve(dbType, req);
        List<Dictionary<string, object?>> rows;
        try
        {
            rows = strategy.Execute<TModel>(filtered, req, wl);
        }
        catch (InvalidOperationException) when (strategy is ServerSideGroupByStrategy)
        {
            // Server-side 翻譯失敗 → fallback to in-process
            rows = new InProcessGroupByStrategy().Execute<TModel>(filtered, req, wl);
        }
        // ... 截斷、回應組裝不變
    }
}

向後相容

• 無參數建構子保留，預設 InProcess 行為不變
• Execute() 新增 dbType 參數有預設值，既有呼叫端不需改動
• Controller 傳入 Wtm.DC.DBType

驗證

• 既有 52 個 Engine 測試全部通過（行為不變）
• 新增 fallback 測試：模擬 ServerSide 拋例外 → 自動降級
• 新增 DI 注入測試

複雜度

中