[CLAUDE] PurchaseEvaluation: multi-NCC per hạng mục — chọn ≥2 NCC-TP trúng thầu/1 hạng mục (mỗi nhà 1 giá riêng)

Đổi winner-truth từ whole-supplier Supplier.IsWinner (Mig 58 liên-danh) sang per-hạng-mục
Quote.IsSelected (Mig 12 dormant hook → nay nguồn-sự-thật); Supplier.IsWinner = DERIVED (== Any IsSelected).
Anh Kiệt LOCKED D1=SUM(IsSelected) · D2=THAY-THẾ · D3=giá-chào-gốc · D4=1HĐ/NCC. 0 bảng/cột mới.

BE:
- SelectWinnerCommand + POST /select-winner: body {supplierIds} → {detailId, supplierIds} (per hạng mục).
- Re-key 5 financial-SUM → WHERE IsSelected: winnerQuoteTotal, submit-guard, CCM-threshold, giaTri, budget-B.
- giaTri bỏ shortcut isSingle→detailsSum (single đổi budget→bid theo D4).
- Derive IsWinner invariant ở MỌI writer: SelectWinner + UpsertQuote + seed + DeleteQuote/DeleteDetail (helper PeWinnerInvariant, fix Bước 4).
- GIỮ IsWinner-derived cho winner-names/existence + CreateContract winners-list.
- Migration BackfillPeQuoteIsSelectedAndWinnerInvariant (data-only 2-chiều IsWinner↔IsSelected, Down no-op).

FE 2-app (PeDetailTabs SHA-identical): HangMucCard per-cell winner grid Detail×NCC + toggle per-detail; NccSelectorRow hạ-cấp read-only summary; giữ derived display.

Test: 7 file update + 8 test mới (per-hạng-mục total, giaTri single-partial, threshold-crossing, derive-invariant, delete-path). 486 PASS.

Flow: fable-clone invest ensemble → anh Kiệt 4-decision → fable-clone review ensemble (6 adjustment) → hmw implement (disk-recover #53) → fable-clone verify (bắt MUST bug delete-path → fix test-before).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Backend/SolutionErp.Api/Controllers/PurchaseEvaluationsController.cs

@@ -179,7 +179,8 @@ public class PurchaseEvaluationsController(IMediator mediator) : ControllerBase
     [HttpPost("{id:guid}/select-winner")]
     public async Task<IActionResult> SelectWinner(Guid id, [FromBody] SelectWinnerBody body, CancellationToken ct)
     {
-        await mediator.Send(new SelectPurchaseEvaluationWinnerCommand(id, body.SupplierIds ?? Array.Empty<Guid>()), ct);
+        await mediator.Send(new SelectPurchaseEvaluationWinnerCommand(
+            id, body.DetailId, body.SupplierIds ?? Array.Empty<Guid>()), ct);
         return NoContent();
     }
 
@@ -359,7 +360,7 @@ public record AddSupplierBody(
     string? DisplayName, string? ContactName, string? ContactEmail, string? ContactPhone,
     string? PaymentTermText, string? Note);
 
-public record SelectWinnerBody(IReadOnlyList<Guid>? SupplierIds);   // [Mig 58] multi-winner: tập đơn vị NCC/TP thắng; [] hoặc null = bỏ chọn (anh Kiệt FDC C5 + CCM multi)
+public record SelectWinnerBody(Guid DetailId, IReadOnlyList<Guid>? SupplierIds);   // [multi-NCC] hạng mục DetailId + tập NCC/TP thắng hạng mục đó; [] hoặc null = bỏ chọn hạng mục này
 
 public record DetailBody(
     string GroupCode, string GroupName, string? ItemCode, string NoiDung, string? DonViTinh,