feat: scaffold agentmon services and k8s deploy

Adds Go microservices (ingest-gateway, event-processor, query-api, web-ui), NATS+Postgres wiring, initial schema/init job, ingress manifests for LAN+tailnet, and a multi-arch image build script.

internal/store/postgres/query.go

@@ -0,0 +1,47 @@
+package postgres
+
+import (
+	"context"
+	"encoding/json"
+	"time"
+)
+
+type EventRow struct {
+	EventID string          `json:"event_id"`
+	TS      time.Time       `json:"ts"`
+	Type    string          `json:"type"`
+	Payload json.RawMessage `json:"payload"`
+}
+
+func (d *DB) ListRecentEvents(ctx context.Context, limit int) ([]EventRow, error) {
+	if limit <= 0 {
+		limit = 100
+	}
+	if limit > 1000 {
+		limit = 1000
+	}
+
+	rows, err := d.sql.QueryContext(ctx, `
+select event_id, ts, type, payload
+from events
+order by ts desc
+limit $1
+`, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var out []EventRow
+	for rows.Next() {
+		var r EventRow
+		if err := rows.Scan(&r.EventID, &r.TS, &r.Type, &r.Payload); err != nil {
+			return nil, err
+		}
+		out = append(out, r)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return out, nil
+}