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/httpapi/server.go

@@ -24,8 +24,8 @@ import (
 	"time"
 
 	"github.com/dtoro/oikos/internal/actuator"
-	"github.com/dtoro/oikos/internal/config"
 	"github.com/dtoro/oikos/internal/adapters/postgres"
+	"github.com/dtoro/oikos/internal/config"
 	"github.com/dtoro/oikos/internal/core/app"
 	"github.com/dtoro/oikos/internal/core/ports"
 	"github.com/dtoro/oikos/internal/httpapi/gen"
@@ -65,10 +65,10 @@ type Server struct {
 	// entities is the entity-aggregate use-case service (Phase 3 of the
 	// hexagonal refactor); entityRepo exposes the idempotency reads the
 	// replay path needs. Wired here until main becomes the composition root.
-	entities    *app.EntityService
-	entityRepo  *db.EntityRepo
-	readModels  ports.ReadModels
-	relService  *app.RelationshipService
+	entities   *app.EntityService
+	entityRepo *db.EntityRepo
+	readModels ports.ReadModels
+	relService *app.RelationshipService
 	// provisioning owns the pct_create flow (Phase 7): spec defaults,
 	// provisioner dispatch, guest registration in the graph.
 	provisioning *app.ProvisioningService
@@ -77,6 +77,10 @@ type Server struct {
 	// execSvc is the run-submission use-case (Phase 4): PolicyService
 	// gating + auto-run/queue dispatch, shared by the MCP tools.
 	execSvc *app.ExecutionService
+	// approvalSvc is the approval-decision use-case (Phase 9): token
+	// verification + execution un-gating, shared by the REST decision
+	// endpoint and the MCP decide_approval path.
+	approvalSvc *app.ApprovalService
 }
 
 // NewHandler builds the full HTTP handler: /healthz (unauthenticated,
@@ -86,7 +90,7 @@ type Server struct {
 // holds a dedicated pooled connection for LISTEN. Callers MUST cancel ctx
 // before closing the pool — otherwise the held connection never releases
 // and pool.Close() deadlocks.
-func NewHandler(ctx context.Context, pool *db.Pool, cfg config.Config, entities *app.EntityService, entityRepo *db.EntityRepo, readModels ports.ReadModels, relService *app.RelationshipService, provisioning *app.ProvisioningService, seeds *app.SeedService, execSvc *app.ExecutionService) http.Handler {
+func NewHandler(ctx context.Context, pool *db.Pool, cfg config.Config, entities *app.EntityService, entityRepo *db.EntityRepo, readModels ports.ReadModels, relService *app.RelationshipService, provisioning *app.ProvisioningService, seeds *app.SeedService, execSvc *app.ExecutionService, approvalSvc *app.ApprovalService) http.Handler {
 	s := &Server{
 		pool:         pool,
 		cfg:          cfg,
@@ -100,6 +104,7 @@ func NewHandler(ctx context.Context, pool *db.Pool, cfg config.Config, entities
 		provisioning: provisioning,
 		seeds:        seeds,
 		execSvc:      execSvc,
+		approvalSvc:  approvalSvc,
 	}
 
 	// Wire secrets backend: Infisical primary with SOPS DR fallback.
@@ -948,10 +953,10 @@ main();
 
 // ListenAndServe runs the API server with graceful shutdown on ctx cancel
 // (SG4): stop accepting, drain in-flight for up to 30s, then exit.
-func ListenAndServe(ctx context.Context, pool *db.Pool, cfg config.Config, entities *app.EntityService, entityRepo *db.EntityRepo, readModels ports.ReadModels, relService *app.RelationshipService, provisioning *app.ProvisioningService, seeds *app.SeedService, execSvc *app.ExecutionService) error {
+func ListenAndServe(ctx context.Context, pool *db.Pool, cfg config.Config, entities *app.EntityService, entityRepo *db.EntityRepo, readModels ports.ReadModels, relService *app.RelationshipService, provisioning *app.ProvisioningService, seeds *app.SeedService, execSvc *app.ExecutionService, approvalSvc *app.ApprovalService) error {
 	srv := &http.Server{
 		Addr:              cfg.APIListen,
-		Handler:           NewHandler(ctx, pool, cfg, entities, entityRepo, readModels, relService, provisioning, seeds, execSvc),
+		Handler:           NewHandler(ctx, pool, cfg, entities, entityRepo, readModels, relService, provisioning, seeds, execSvc, approvalSvc),
 		ReadHeaderTimeout: 10 * time.Second,
 	}