feat(jobs): emit job.enqueue + worktree.pruned audit rows

Deferred audit retrofits from Plan #5 self-review:
- WebhookNotifier now records a job.enqueue audit row after each
  successful repo.Enqueue (best-effort: failures are warn-logged, not
  propagated). Added optional audit.Recorder + *slog.Logger params to
  NewWebhookNotifier.
- WorktreePrune.executionPhase now records a worktree.pruned audit row
  after each successful FinishPruneSuccess. Added optional audit.Recorder
  param to NewWorktreePrune.
- app.go wires the existing auditRec into both constructors.
- integration_test.go: drop the _ = auditRec suppression and pass
  auditRec into the webhook notifier so the closed-loop test exercises
  the audit emit path.

internal/jobs/runners/worktree_prune.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/google/uuid"
 
+	"github.com/yan1h/agent-coding-workflow/internal/audit"
 	"github.com/yan1h/agent-coding-workflow/internal/infra/notify"
 )
 
@@ -45,19 +46,21 @@ type WorktreePruneConfig struct {
 
 // WorktreePrune is the B runner.
 type WorktreePrune struct {
-	repo WorktreePruneRepo
-	gitr WorktreePruner
-	disp Dispatcher
-	cfg  WorktreePruneConfig
-	log  *slog.Logger
+	repo  WorktreePruneRepo
+	gitr  WorktreePruner
+	disp  Dispatcher
+	cfg   WorktreePruneConfig
+	log   *slog.Logger
+	audit audit.Recorder
 }
 
-// NewWorktreePrune constructs the runner.
-func NewWorktreePrune(repo WorktreePruneRepo, gitr WorktreePruner, disp Dispatcher, cfg WorktreePruneConfig, log *slog.Logger) *WorktreePrune {
+// NewWorktreePrune constructs the runner. rec is optional; when non-nil the
+// runner emits a worktree.pruned audit row after each successful prune.
+func NewWorktreePrune(repo WorktreePruneRepo, gitr WorktreePruner, disp Dispatcher, cfg WorktreePruneConfig, log *slog.Logger, rec audit.Recorder) *WorktreePrune {
 	if log == nil {
 		log = slog.Default()
 	}
-	return &WorktreePrune{repo: repo, gitr: gitr, disp: disp, cfg: cfg, log: log}
+	return &WorktreePrune{repo: repo, gitr: gitr, disp: disp, cfg: cfg, log: log, audit: rec}
 }
 
 // Run executes warning phase then execution phase.
@@ -117,6 +120,19 @@ func (r *WorktreePrune) executionPhase(ctx context.Context) {
 		}
 		if err := r.repo.FinishPruneSuccess(ctx, w.ID); err != nil {
 			r.log.Error("worktree_prune.finish_success", "worktree_id", w.ID, "err", err.Error())
+			continue
+		}
+		if r.audit != nil {
+			if rerr := r.audit.Record(ctx, audit.Entry{
+				Action:     "worktree.pruned",
+				TargetType: "worktree",
+				TargetID:   w.ID.String(),
+				Metadata: map[string]any{
+					"branch": w.Branch,
+				},
+			}); rerr != nil {
+				r.log.Warn("worktree_prune.audit_failed", "worktree_id", w.ID, "err", rerr.Error())
+			}
 		}
 	}
 }