feat: Phase 3 J/K/L (Sell Decision, Trade Execution, Portfolio Reconciliation) + fix pre-existing build/boot breakage

Completes VS-10/VS-12/VS-14 and makes the solution and Host actually
build and boot for the first time on this branch (main did not build
before this commit).

Root-cause fixes required to reach a green build/boot (not scoped to
J/K/L but blocking any verification of it):
- Restore Polly PackageVersion accidentally deleted from
  Directory.Packages.props (broke KArtSell.Host).
- Remove MediatR dependency from Compliance/VS-04 (package was never
  installed; ICommand/ICommandHandler/IMediator never existed) and
  wire Endpoint -> Handler directly per this repo's convention.
- Migrate FastEndpoints v5 API calls (SendOkAsync/SendAsync/
  SendCreatedAtAsync/SendNotFoundAsync, Description().WithName()) to
  the v7 Send.* fluent API across ~10 endpoint files.
- Fix migrations 0036/0038/0039/0040: rewritten from invalid T-SQL
  (`IF NOT EXISTS ... BEGIN ... END`) to idiomatic Postgres
  (`CREATE TABLE/INDEX IF NOT EXISTS`) — these could not apply to any
  fresh database before this fix.
- Collapse 3 duplicate cross-cutting abstractions that shadowed the
  BuildingBlocks versions and caused type-mismatch compile errors:
  IKrxDataService, IOutboxWriter (ReconcileTradeHandler), IClock
  (ApprovalWorkflow/ApprovalPolicy).
- Inject IClock (BuildingBlocks.Time) in place of direct
  DateTime.Now/UtcNow across 19 files to satisfy the architecture
  test AGENTS.md#DateTime-abstraction rule (13/13 architecture tests
  now pass, was 12/13).
- Register all new and previously-unregistered slices in
  Program.cs DI (SellDecision, TradeExecution, PortfolioReconciliation,
  Compliance, Features/ApprovalWorkflow) — the Host had never
  successfully completed a boot with this code present.
- Disable ("[DontRegister]") the older, route-colliding
  ApprovalWorkflow/ (Workstream H) endpoint set in favor of
  Features/ApprovalWorkflow/ (Workstream G, matches the documented
  Features/<Slice>/ convention); kept for its existing test coverage.
  See TECH_DEBT-017 for the follow-up decision needed.

Verified: dotnet build 0 errors/0 warnings; architecture tests 13/13;
unit tests 54/54 + 18/18; integration tests 34/36 (2 failures are a
local test-DB migration-journal/schema mismatch, not a code defect);
Host boots cleanly and registers all 34 endpoints.

New tech debt recorded: DEBT-017 (duplicate VS-03 implementation),
DEBT-018 (outbox write not co-transactional with entity write in
TradeExecution/PortfolioReconciliation), DEBT-019 (duplicate
BuildingBlocks-shadowing abstractions, partially resolved).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/KArtSell.Modules.ModelOperations/Features/ApprovalWorkflow/Endpoints.cs

@@ -1,12 +1,14 @@
 namespace KArtSell.Modules.ModelOperations.Features.ApprovalWorkflow;
 
 using FastEndpoints;
+using KArtSell.BuildingBlocks.Time;
 using KArtSell.Modules.ModelOperations.Domain.ApprovalWorkflow;
+using Microsoft.AspNetCore.Http;
 
 public record CreateApprovalRequest(Guid ModelId, DateOnly EffectiveAt, string Justification);
 public record CreateApprovalResponse(Guid Id, string Status, DateTime CreatedAt);
 
-public class CreateApprovalEndpoint : EndpointWithoutRequests<CreateApprovalResponse>
+public class CreateApprovalEndpoint : EndpointWithoutRequest<CreateApprovalResponse>
 {
     private readonly CreateApprovalProposalHandler _handler;
     private readonly ApprovalWorkflowSql _sql;
@@ -32,7 +34,7 @@ public class CreateApprovalEndpoint : EndpointWithoutRequests<CreateApprovalResp
         var proposalId = await _handler.Handle(userEmail, userRole, request!.ModelId, request.EffectiveAt, request.Justification, Guid.NewGuid(), ct);
         var proposal = await _sql.GetProposalAsync(proposalId, ct);
 
-        await SendCreatedAtAsync<CreateApprovalEndpoint>(new { id = proposalId }, new CreateApprovalResponse(proposalId, "DRAFT", proposal!.CreatedAt), cancellation: ct);
+        await Send.CreatedAtAsync<CreateApprovalEndpoint>(new { id = proposalId }, new CreateApprovalResponse(proposalId, "DRAFT", proposal!.CreatedAt), cancellation: ct);
     }
 }
 
@@ -54,12 +56,12 @@ public class GetApprovalsEndpoint : Endpoint<GetApprovalsRequest, GetApprovalsRe
 
     public override async Task HandleAsync(GetApprovalsRequest req, CancellationToken ct)
     {
-        var status = req.Status != null ? Enum.Parse<ApprovalStatus>(req.Status, ignoreCase: true) : null;
+        ApprovalStatus? status = req.Status != null ? Enum.Parse<ApprovalStatus>(req.Status, ignoreCase: true) : null;
         var proposals = await _sql.ListProposalsAsync(status, req.ModelId, req.Limit, req.Offset, ct);
 
         var items = proposals.Select(p => new ApprovalDto(p.Id, p.ModelId, p.Status.ToString(), p.CreatedBy, p.CreatedAt, p.Justification)).ToList();
 
-        await SendAsync(new GetApprovalsResponse(items, items.Count, (items.Count + req.Limit - 1) / req.Limit), cancellation: ct);
+        await Send.OkAsync(new GetApprovalsResponse(items, items.Count, (items.Count + req.Limit - 1) / req.Limit), ct);
     }
 }
 
@@ -71,11 +73,13 @@ public class ApproveApprovalEndpoint : Endpoint<ApproveApprovalRequest, ApproveA
 {
     private readonly ApproveApprovalHandler _handler;
     private readonly ApprovalWorkflowSql _sql;
+    private readonly IClock _clock;
 
-    public ApproveApprovalEndpoint(ApproveApprovalHandler handler, ApprovalWorkflowSql sql)
+    public ApproveApprovalEndpoint(ApproveApprovalHandler handler, ApprovalWorkflowSql sql, IClock clock)
     {
         _handler = handler;
         _sql = sql;
+        _clock = clock;
     }
 
     public override void Configure()
@@ -94,6 +98,6 @@ public class ApproveApprovalEndpoint : Endpoint<ApproveApprovalRequest, ApproveA
         await _handler.Handle(proposalId, userEmail, userRole, req.ApprovalNotes, evidence, Guid.NewGuid(), ct);
 
         var proposal = await _sql.GetProposalAsync(proposalId, ct);
-        await SendAsync(new ApproveApprovalResponse(proposalId, "APPROVED", proposal!.ApprovedAt ?? DateTime.UtcNow), cancellation: ct);
+        await Send.OkAsync(new ApproveApprovalResponse(proposalId, "APPROVED", proposal!.ApprovedAt ?? _clock.UtcNow.UtcDateTime), ct);
     }
 }