feat(harness): per-run auto-approval of layer-2 proposals for model measurement

런 옵션 auto_approve_after_s(runs 열·POST /runs)를 추가한다. 값이 양수면 하네스가 제안
등록 뒤 그 지연만큼 기다렸다가 스스로 승인(actor auto)하고 HITL 버튼 경로와 같은 방식으로
조치를 실행(actor ai-approved, MarkProposalExecuted)한다. 사람 없이 모델 비교 캠페인을
반복하기 위한 측정 모드로, MTTA는 지연값으로 고정되고 판정 로직은 그대로다(2층 판정은
ai-approved 조치에서 나온다). 이미 결정·만료된 제안과 기록 전용 조치는 API 경로와 같이
처리한다.

harness/store.go

@@ -25,6 +25,7 @@ CREATE TABLE IF NOT EXISTS runs (
   notes        text
 );
 ALTER TABLE runs ADD COLUMN IF NOT EXISTS model text;  -- LLM requested for the run's diagnoses (campaign-level model selection, 2026-10-14)
+ALTER TABLE runs ADD COLUMN IF NOT EXISTS auto_approve_after_s int;  -- measurement mode: the harness approves + executes layer-2 proposals after this delay (2026-10-15)
 CREATE TABLE IF NOT EXISTS scenarios (
   scenario_id         text PRIMARY KEY,
   path                text NOT NULL,
@@ -120,8 +121,8 @@ func (s *Store) UpsertScenarios(ctx context.Context, m map[string]*Scenario) err
 	return nil
 }
 
-func (s *Store) CreateRun(ctx context.Context, id, campaign string, driftBefore *int, gitSHA, notes, model string) error {
-	_, err := s.pool.Exec(ctx, `INSERT INTO runs (run_id,campaign,drift_before,git_sha,notes,model) VALUES ($1,$2,$3,$4,$5,$6)`, id, campaign, driftBefore, nz(gitSHA), nz(notes), nz(model))
+func (s *Store) CreateRun(ctx context.Context, id, campaign string, driftBefore *int, gitSHA, notes, model string, autoApproveAfterS *int) error {
+	_, err := s.pool.Exec(ctx, `INSERT INTO runs (run_id,campaign,drift_before,git_sha,notes,model,auto_approve_after_s) VALUES ($1,$2,$3,$4,$5,$6,$7)`, id, campaign, driftBefore, nz(gitSHA), nz(notes), nz(model), autoApproveAfterS)
 	return err
 }
 
@@ -223,11 +224,12 @@ type RunRow struct {
 	GitSHA      *string    `json:"git_sha"`
 	Status      string     `json:"status"`
 	Notes       *string    `json:"notes"`
-	Model       *string    `json:"model"` // nil for runs before campaign-level model selection
+	Model       *string    `json:"model"`                // nil for runs before campaign-level model selection
+	AutoApprove *int       `json:"auto_approve_after_s"` // nil/0 = human approval (Discord); >0 = harness auto-approved layer-2 proposals after this delay
 }
 
 func (s *Store) Runs(ctx context.Context, runID string) ([]RunRow, error) {
-	rows, err := s.pool.Query(ctx, `SELECT run_id,campaign,started_at,finished_at,drift_before,drift_after,git_sha,status,notes,model FROM runs WHERE ($1='' OR run_id=$1) ORDER BY started_at DESC LIMIT 100`, runID)
+	rows, err := s.pool.Query(ctx, `SELECT run_id,campaign,started_at,finished_at,drift_before,drift_after,git_sha,status,notes,model,auto_approve_after_s FROM runs WHERE ($1='' OR run_id=$1) ORDER BY started_at DESC LIMIT 100`, runID)
 	if err != nil {
 		return nil, err
 	}
@@ -235,7 +237,7 @@ func (s *Store) Runs(ctx context.Context, runID string) ([]RunRow, error) {
 	var out []RunRow
 	for rows.Next() {
 		var r RunRow
-		if err := rows.Scan(&r.RunID, &r.Campaign, &r.StartedAt, &r.FinishedAt, &r.DriftBefore, &r.DriftAfter, &r.GitSHA, &r.Status, &r.Notes, &r.Model); err != nil {
+		if err := rows.Scan(&r.RunID, &r.Campaign, &r.StartedAt, &r.FinishedAt, &r.DriftBefore, &r.DriftAfter, &r.GitSHA, &r.Status, &r.Notes, &r.Model, &r.AutoApprove); err != nil {
 			return nil, err
 		}
 		out = append(out, r)