perf: incremental render scale, SQL pagination and observability

- BIRD filter chunking (500 CIDR); bounded job worker pool
- ListModulesPage SQL push-down; revision diff limit; batch revision prune
- DB pool tuning; Prometheus pipeline/job metrics
- Coalesce module_refresh via idempotency; GET /jobs/{id}/report
- JobAuditWriter foundation for job_audit persistence

Co-authored-by: Cursor <[email protected]>

internal/repository/job_audit.go

@@ -0,0 +1,50 @@
+package repository
+
+import (
+	"context"
+	"encoding/json"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// JobAuditWriter persists async job lifecycle rows to job_audit (optional cross-process queue foundation).
+type JobAuditWriter struct {
+	pool *pgxpool.Pool
+}
+
+func NewJobAuditWriter(pool *pgxpool.Pool) *JobAuditWriter {
+	if pool == nil {
+		return nil
+	}
+	return &JobAuditWriter{pool: pool}
+}
+
+// UpsertRunning inserts or updates a running job row (best-effort).
+func (w *JobAuditWriter) UpsertRunning(ctx context.Context, tenantID, jobID, kind string, idempotencyKey *string, meta map[string]any) {
+	if w == nil || w.pool == nil {
+		return
+	}
+	metaJSON, _ := json.Marshal(meta)
+	var idem any
+	if idempotencyKey != nil && *idempotencyKey != "" {
+		idem = *idempotencyKey
+	}
+	_, _ = w.pool.Exec(ctx, `
+		INSERT INTO job_audit (id, tenant_id, kind, status, idempotency_key, meta_json, created_at, started_at)
+		VALUES ($1::uuid, $2::uuid, $3, 'running', $4, $5::jsonb, now(), now())
+		ON CONFLICT (tenant_id, idempotency_key) WHERE idempotency_key IS NOT NULL
+		DO UPDATE SET status='running', started_at=now(), meta_json=EXCLUDED.meta_json`,
+		jobID, tenantID, kind, idem, metaJSON)
+}
+
+// MarkTerminal updates job_audit terminal state (best-effort).
+func (w *JobAuditWriter) MarkTerminal(ctx context.Context, tenantID, jobID, status string, errMsg *string, finishedAt time.Time) {
+	if w == nil || w.pool == nil {
+		return
+	}
+	_, _ = w.pool.Exec(ctx, `
+		UPDATE job_audit SET status=$3, error_message=$4, finished_at=$5
+		WHERE id=$1::uuid AND tenant_id=$2::uuid`,
+		jobID, tenantID, status, errMsg, finishedAt.UTC())
+}