Refactor sales pipeline: ShopPO, Invoice, SysConfig models

Major refactor replacing Sale/Order with ShopPO → Invoice → LoadingSheet flow. Removed legacy Sale/Order models and features; introduced ShopPO, ShopPOItem, Invoice, LoadingSheetOrder, and SysConfig models. Updated related entities, enums, repositories, and controllers. Added new migrations for schema changes and system config. Overhauled business logic and DI registrations. Updated documentation with migration plan.

Distribution/Features/SysConfig/SysConfigController.cs

@@ -0,0 +1,53 @@
+using Distribution.Infra.Authorization;
+using Distribution.Models;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Distribution.Features.SysConfig;
+
+[ApiController]
+[Route("api/sys-config")]
+public class SysConfigController(SysConfigService service, ICurrentUserService currentUser) : ControllerBase
+{
+    [HttpGet]
+    public async Task<IActionResult> GetAll() =>
+        Ok(await service.GetAllAsync());
+
+    // Typed shortcut — must be declared before {key} to take precedence
+    [HttpGet("invoice-creation-mode")]
+    public async Task<IActionResult> GetInvoiceCreationMode()
+    {
+        var mode = await service.GetInvoiceCreationModeAsync();
+        return Ok(new { Mode = mode });
+    }
+
+    [HttpPut("invoice-creation-mode")]
+    public async Task<IActionResult> SetInvoiceCreationMode(SetInvoiceCreationModeRequest request, CancellationToken ct)
+    {
+        var userId = currentUser.UserId ?? throw new UnauthorizedAccessException();
+        try
+        {
+            var result = await service.SetAsync(SysConfigService.KeyInvoiceCreationMode, request.Mode.ToString(), userId, ct);
+            return Ok(result);
+        }
+        catch (InvalidOperationException ex) { return BadRequest(new { error = ex.Message }); }
+    }
+
+    [HttpGet("{key}")]
+    public async Task<IActionResult> GetByKey(string key)
+    {
+        var result = await service.GetByKeyAsync(key);
+        return result is null ? NotFound() : Ok(result);
+    }
+
+    [HttpPut("{key}")]
+    public async Task<IActionResult> Set(string key, SetSysConfigRequest request, CancellationToken ct)
+    {
+        var userId = currentUser.UserId ?? throw new UnauthorizedAccessException();
+        try
+        {
+            var result = await service.SetAsync(key, request.Value, userId, ct);
+            return Ok(result);
+        }
+        catch (InvalidOperationException ex) { return BadRequest(new { error = ex.Message }); }
+    }
+}