refactor(db): port metrics storage + service domains to sqlc

First tranche of the ~300-site raw SQL port. Metrics: node/service/
instance rows via generated queries; aggregation moved off TimescaleDB's
time_bucket onto portable date_bin (PG14+); interval uptime returns epoch
seconds; per-container writes dropped (container_metrics FKs a different
model — collector shape never matched). Domains: all reads/writes through
sqlcdb including the create transaction via WithTx; default-domain and
services.domain invariants unchanged. Both paths covered by live
Postgres tests gated on METRICS_TEST_DSN.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/internal/api/domains_test.go

@@ -1,6 +1,28 @@
 package api
 
-import "testing"
+import (
+	"context"
+	"os"
+	"strings"
+	"testing"
+
+	"containr/internal/database"
+	"containr/internal/database/sqlcdb"
+
+	"github.com/google/uuid"
+)
+
+func testDSNString(t *testing.T) string {
+	t.Helper()
+	dsn := os.Getenv("METRICS_TEST_DSN")
+	if dsn == "" {
+		dsn = os.Getenv("DATABASE_URL")
+	}
+	if dsn == "" {
+		t.Skip("METRICS_TEST_DSN not set")
+	}
+	return dsn
+}
 
 func TestDNSLabel(t *testing.T) {
 	cases := map[string]string{
@@ -24,3 +46,100 @@ func TestDNSLabelLengthCap(t *testing.T) {
 		t.Fatalf("label over 63 chars: %d", len(got))
 	}
 }
+
+// Live invariant test against real Postgres — set METRICS_TEST_DSN (or
+// DATABASE_URL). Verifies the generated domain queries preserve the
+// default-domain and legacy services.domain invariants.
+func TestServiceDomainsLiveInvariants(t *testing.T) {
+	dsn := testDSNString(t)
+	db, err := database.NewConnection(dsn)
+	if err != nil {
+		t.Fatalf("connect: %v", err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	q := sqlcdb.New(db.DB)
+
+	userID := uuid.New()
+	projectID := uuid.New()
+	envID := uuid.New()
+	serviceID := uuid.New()
+	suffix := strings.ReplaceAll(serviceID.String()[:8], "-", "")
+
+	must := func(err error) {
+		t.Helper()
+		if err != nil {
+			t.Fatalf("setup: %v", err)
+		}
+	}
+	_, err = db.Exec(`INSERT INTO users (id, email, password_hash, name) VALUES ($1, $2, 'x', 'test')`,
+		userID, "domtest-"+suffix+"@test.local")
+	must(err)
+	_, err = db.Exec(`INSERT INTO projects (id, name, owner_id, is_approved) VALUES ($1, $2, $3, true)`,
+		projectID, "domtest-"+suffix, userID)
+	must(err)
+	_, err = db.Exec(`INSERT INTO environments (id, name, project_id) VALUES ($1, 'production', $2)`,
+		envID, projectID)
+	must(err)
+	_, err = db.Exec(`INSERT INTO services (id, name, project_id, environment_id, service_type, source_type)
+		VALUES ($1, 'domtest-`+suffix+`', $2, $3, 'web', 'image')`,
+		serviceID, projectID, envID)
+	must(err)
+	defer func() {
+		_, _ = db.Exec(`DELETE FROM users WHERE id = $1`, userID)
+	}()
+
+	d1, err := q.CreateServiceDomain(ctx, sqlcdb.CreateServiceDomainParams{
+		ServiceID: serviceID, Domain: "a-" + suffix + ".example.com", IsDefault: true})
+	if err != nil {
+		t.Fatalf("create d1: %v", err)
+	}
+	d2, err := q.CreateServiceDomain(ctx, sqlcdb.CreateServiceDomainParams{
+		ServiceID: serviceID, Domain: "b-" + suffix + ".example.com", IsDefault: false})
+	if err != nil {
+		t.Fatalf("create d2: %v", err)
+	}
+
+	syncDefaultDomain(db, serviceID)
+	var legacy string
+	if err := db.QueryRow(`SELECT domain FROM services WHERE id = $1`, serviceID).Scan(&legacy); err != nil {
+		t.Fatalf("read legacy: %v", err)
+	}
+	if legacy != d1.Domain {
+		t.Fatalf("legacy domain = %q, want %q", legacy, d1.Domain)
+	}
+
+	// Switch default: exactly one row stays default, legacy follows.
+	if err := q.ClearServiceDomainDefault(ctx, serviceID); err != nil {
+		t.Fatalf("clear: %v", err)
+	}
+	if _, err := q.SetServiceDomainDefault(ctx, sqlcdb.SetServiceDomainDefaultParams{
+		ID: d2.ID, ServiceID: serviceID}); err != nil {
+		t.Fatalf("set default: %v", err)
+	}
+	syncDefaultDomain(db, serviceID)
+	if err := db.QueryRow(`SELECT domain FROM services WHERE id = $1`, serviceID).Scan(&legacy); err != nil {
+		t.Fatalf("read legacy2: %v", err)
+	}
+	if legacy != d2.Domain {
+		t.Fatalf("legacy after switch = %q, want %q", legacy, d2.Domain)
+	}
+
+	doms := loadServiceDomains(db, serviceID)
+	if len(doms) != 2 || !doms[0].IsDefault || doms[0].Domain != d2.Domain {
+		t.Fatalf("list order wrong: %+v", doms)
+	}
+
+	// Deleting the default falls back to the remaining domain.
+	if _, err := q.DeleteServiceDomain(ctx, sqlcdb.DeleteServiceDomainParams{
+		ID: d2.ID, ServiceID: serviceID}); err != nil {
+		t.Fatalf("delete d2: %v", err)
+	}
+	syncDefaultDomain(db, serviceID)
+	if err := db.QueryRow(`SELECT domain FROM services WHERE id = $1`, serviceID).Scan(&legacy); err != nil {
+		t.Fatalf("read legacy3: %v", err)
+	}
+	if legacy != d1.Domain {
+		t.Fatalf("legacy after delete = %q, want %q", legacy, d1.Domain)
+	}
+}