M5: action gate + review inbox — edit distance captured for real

SharedKernel:
- ActionRisk (risk lives on the action) + GatePolicy (the pure autonomy x risk matrix:
  Read never holds, Draft/Publish hold unless Autonomous, Destructive ALWAYS holds).
- IActionGate (AgentActionProposal -> execute|hold) and IBoardWriter.AttachArtifactAsync.

Governance:
- ReviewItem (held action: artifact, child titles, trace, decision, edit distance) in a new
  review_items table (AddReviewItems migration).
- ActionGate: hold -> ReviewItem + "action.held" audit; autonomous -> execute + audit.
- HeldActionExecutor: writes the artifact onto the task and creates the child tasks via
  IBoardWriter (implemented by OrgBoard — no cross-module table access).
- Review inbox API: GET /api/governance/reviews (scope-filtered to where the caller may
  approve), POST /reviews/{id}/approve (optional edited content/children -> normalized
  edit distance recorded — the north-star metric), POST /reviews/{id}/sendback. Deciding
  twice is 409; Members are 403.

Assembler:
- OutputParser (numbered-list child titles, conservative) and the executor now hands every
  completed run's proposal to the gate.

OrgBoard: WorkItem.AttachArtifact + BoardWriter.AttachArtifactAsync.

Verified: build green; ArchitectureTests 8/8; IntegrationTests 41/41 incl. the full M5
acceptance — Aria (gated) proposes a spec, it waits in the inbox with its trace, a Member is
403'd, the owner edits-and-approves, the spec + four child stories land on the board, edit
distance > 0 is recorded and audited; Quill (autonomous) executes straight to the board;
destructive holds even for an autonomous seat and can be sent back. Plus the GatePolicy matrix.

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

src/Modules/TeamUp.Modules.Governance/GovernanceModule.cs

@@ -5,7 +5,9 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using TeamUp.Modules.Governance.Auditing;
 using TeamUp.Modules.Governance.Endpoints;
+using TeamUp.Modules.Governance.Gate;
 using TeamUp.Modules.Governance.Persistence;
+using TeamUp.SharedKernel.Ai;
 using TeamUp.SharedKernel.Auditing;
 using TeamUp.SharedKernel.Modularity;
 using TeamUp.SharedKernel.Persistence;
@@ -25,6 +27,8 @@ public sealed class GovernanceModule : IModule
         services.AddDbContext<GovernanceDbContext>(options => options.UseNpgsql(connectionString));
         services.AddScoped<IModuleDbContext>(sp => sp.GetRequiredService<GovernanceDbContext>());
         services.AddScoped<IAuditLog, AuditLog>();
+        services.AddScoped<HeldActionExecutor>();
+        services.AddScoped<IActionGate, ActionGate>();
         services.TryAddSingleton(TimeProvider.System);
     }