feat: Phase 9 gaps closed — ApprovalService.Decide convergence, execlog fold, execworker poller

- ApprovalService (core/app/approval.go) + ApprovalRepo (postgres adapter) with
  full decide transaction: HMAC token verify, approval flip, execution un-gate,
  session-scoped window keys (+session suffix matching GovernanceStore gate),
  nomos session flip, audit+event on failure abort. httpapi DecideApproval now
  a thin presenter delegating to the service. ListPending payload format fixed
  (json.Unmarshal not raw-wrap).
- execlog folded into postgres adapter: internal/execlog deleted, NewExecutionLog
  / ReadExecutionLog live in the db package, callers updated (mcp, httpapi).
- execworker poller over ExecutionService.DispatchQueued: advisory lock leak
  fixed (defer/recover per execution), correlation_id preserved via Finalize
  event emission (ExecRunRepo.Finalize now emits execution.{status} with
  correlation_id from the row).
- Phase 8 session export-rename completed: Store, New, and all 53 methods
  exported; cmd/nomos/ agent.go fixed to use session.PendingContinuation etc.
- Coverage gates: ExecutionService.Submit 93.1%, PolicyService.Decide 100%.
- Plans index updated, VERSION bumped to 0.36.0.

internal/core/ports/governance.go

@@ -83,17 +83,32 @@ type ExecutionRepository interface {
 type ApprovalDecideInput struct {
 	ApprovalID domain.UUID
 	Token      string
-	Approved   bool
+	Status     string // "approved" | "denied" | "revoked"
 	Actor      string
 	Audit      []AuditEntry
 	Event      *Event
 }
 
+// ApprovalResume identifies an un-gated execution the driving adapter should
+// dispatch after an approved decision (SSH work is adapter-specific).
+type ApprovalResume struct {
+	ExecutionID domain.UUID
+	TargetSlug  string
+	Action      string
+}
+
+// ApprovalDecideResult carries the updated approval and, on approve, the
+// linked execution to resume.
+type ApprovalDecideResult struct {
+	Approval domain.Approval
+	Resume   *ApprovalResume
+}
+
 // ApprovalRepository is the approval aggregate.
 type ApprovalRepository interface {
 	ListPending(ctx context.Context, entityID domain.UUID, limit int) ([]domain.Approval, error)
 
-	Decide(ctx context.Context, input ApprovalDecideInput) (domain.Approval, error)
+	Decide(ctx context.Context, input ApprovalDecideInput) (ApprovalDecideResult, error)
 }
 
 // GovernanceStore is the policy read model: the facts the gating decision