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>

TECH_DEBT_REGISTER.md

@@ -49,6 +49,9 @@
 | DEBT-007 | Newtonsoft.Json override | Medium (2) | Medium (2) | Completed | Fixed in 88ea5ed: CA1848/CA1859 actual implementation. LoggerMessage + HashSet/Dictionary. | @claude | - |
 | DEBT-008 | Namespace consistency | Medium (2) | Low (1) | Accepted | All projects use RootNamespace=KArtSell.Aegis; AssemblyName retained per-project for DLL clarity. Trade-off accepted: DLL clarity > namespace alignment. No action. | @claude | PR 4d |
 | DEBT-016 | VS-02 mislabeled domain | Medium (2) | Low (1) | Backlog | Existing code `VS02_SyncSecurityMasterEndpoint.cs`, `VS02_SecurityMasterJobs.cs`, `VS02_SecurityMasterPolicy.cs` implement RBAC rule synchronization (access control), not financial security master data (listing/delisting/product structure). Dead code: endpoints disabled (DISABLED comment), schema `security_master.rules` table never migrated, never deployed. Correct domain documented in `docs/CURRENT/SLICE_SPECS/VS-02-SLICE_SPEC.md` (financial PIT). Removal decision deferred pending architect review (PR recommended). | @claude | docs/CURRENT/SLICE_SPECS/VS-02-SLICE_SPEC.md |
+| DEBT-017 | Duplicate VS-03 Approval Workflow implementation | High (3) | Medium (2) | Backlog | Two independent, functionally-identical VS-03 maker-checker slices exist: `ApprovalWorkflow/` (Workstream H, own `ApprovalProposal`/`IClock`/`IOutbox` types) and `Features/ApprovalWorkflow/` (Workstream G, matches documented `Features/<Slice>/` convention). Both mapped the same routes (`/approvals`, `/approvals/{id}`, `/approvals/{id}/approve`), which crashed Host startup with a duplicate-route/missing-DI error the first time the app was actually booted (2026-08-07 — apparently never booted successfully before). Old set annotated `[DontRegister]` (FastEndpoints) 2026-08-07 to unblock boot; code and its test file (`ApprovalWorkflowTests.cs`) kept for now. Needs an architect decision: delete the old slice entirely (and its test) or intentionally keep both for a reason not yet documented. | @claude | Session 2026-08-07 (Phase 3 J/K/L hardening) |
+| DEBT-018 | Outbox write not co-transactional with entity write | Medium (2) | Medium (2) | Backlog | `TradeExecution/TradeHandlers.cs` (`TradeOutboxPublisher`) and `PortfolioReconciliation/ReconcileTradeHandler.cs` open a second, separate connection/transaction to write the outbox message after the trade/holding write already committed on its own connection. A crash between the two leaves the entity updated but no outbox event emitted (silent, non-atomic). Proper fix: thread a shared `NpgsqlTransaction` through `TradeSql`/`ReconciliationSql` mutation methods so entity insert + outbox insert commit together, matching `DapperModelOperationRequestRepository`'s pattern. | @claude | Session 2026-08-07 (Phase 3 J/K/L hardening) |
+| DEBT-019 | Multiple duplicate cross-cutting abstractions (`IClock`, `IOutboxWriter`, `IKrxDataService`) | Medium (2) | Low (1) | Completed (partial) | Found and collapsed 3 separate cases where a slice reinvented an abstraction that already existed in `KArtSell.BuildingBlocks`: a second `IKrxDataService` (deleted, `ShadowRun.Services`), a second `IOutboxWriter`/`WriteAsync<T>` in `ReconcileTradeHandler.cs` (removed, switched to `BuildingBlocks.Reliability.IOutboxWriter`), and a second `IClock`/`SystemClock` in `ApprovalWorkflow/ApprovalPolicy.cs` (removed, switched to `BuildingBlocks.Time.IClock`). Root cause: successive sessions implementing a slice without searching `BuildingBlocks` first. Recommend a pre-implementation checklist step ("does this abstraction already exist in BuildingBlocks?") for future slices. | @claude | Session 2026-08-07 (Phase 3 J/K/L hardening) |
 
 ---