refactor(db): port service clone/move ops to sqlc

Tranche 2: cloneServiceRow's INSERT...SELECT (volumes and traefik_labels
now read straight from the source row — traefik_labels was silently
dropped before, and the jsonb param round-trip goes away), domain and
variable copies, name-conflict counts, move UPDATE, project owner check.
Also fixes serviceWriteAccess: user_id is a context string, not a
uuid.UUID — the tranche-1 cast silently failed owner checks for
non-admins. Live tests cover the domain invariants and a full clone
round-trip (config, domains, variables).

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

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

app/backend/internal/api/domains.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"fmt"
 	"net"
 	"net/http"
 	"regexp"
@@ -210,7 +211,7 @@ func basicAuthUsernames(encoded string) []string {
 // serviceWriteAccess mirrors the service update handler's access check.
 func serviceWriteAccess(c *gin.Context, db *database.DB, serviceID uuid.UUID) bool {
 	userID, _ := c.Get("user_id")
-	uid, _ := userID.(uuid.UUID)
+	uid, _ := uuid.Parse(fmt.Sprint(userID))
 	ok, err := sqlcdb.New(db.DB).ServiceWriteAccess(context.Background(), sqlcdb.ServiceWriteAccessParams{
 		ID:      serviceID,
 		OwnerID: uid,