fix: DEBT-025/026 - wire Draft->Proposed transition and GET /approvals/{id}

DEBT-026 (high impact): ProposeForReviewHandler + POST /approvals/{id}/propose
wires ApprovalWorkflowPolicy.CanProposeForReview, which previously had no
Handler/Endpoint calling it. Before this, a proposal created via POST
/approvals could never reach Approved/Active through the running application
- the maker-checker gate was not completable end-to-end via HTTP.

DEBT-025 (medium impact): GetApprovalByIdEndpoint (GET /approvals/{id}) +
ApprovalWorkflowSql.GetEvidenceForProposalAsync make evidence attached during
approval (PBO/DSR/OOS artifact links) readable via HTTP instead of only by
querying model_operations.approval_evidence directly.

Both discovered while resolving DEBT-017 earlier the same session. 4 new
tests added. dotnet build -c Release clean. Not verified against a live
database (no SSH tunnel open in this environment) - see
TECH_DEBT_REGISTER.md and WBS_PROGRESS_TRACKER.csv AEG-VS-26-01 for the
honest verification status; do not mark COMPLETED until a real Postgres
run passes.

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

src/KArtSell.Host/Program.cs

@@ -211,6 +211,7 @@ builder.Services.AddScoped<KArtSell.Modules.ModelOperations.PortfolioReconciliat
 // Approval Workflow (VS-26, formerly VS-03; maker-checker — see docs/DECISIONS/ADR-WBS-001-slice-renumbering.md)
 builder.Services.AddScoped(sp => new KArtSell.Modules.ModelOperations.Features.ApprovalWorkflow.ApprovalWorkflowSql(connectionString));
 builder.Services.AddScoped<KArtSell.Modules.ModelOperations.Features.ApprovalWorkflow.CreateApprovalProposalHandler>();
+builder.Services.AddScoped<KArtSell.Modules.ModelOperations.Features.ApprovalWorkflow.ProposeForReviewHandler>();
 builder.Services.AddScoped<KArtSell.Modules.ModelOperations.Features.ApprovalWorkflow.ApproveApprovalHandler>();
 builder.Services.AddScoped<KArtSell.Modules.ModelOperations.Features.ApprovalWorkflow.ActivateModelHandler>();