feat(ops-api/site-mappings): provision monitoring DB pool and readiness check

Open a separate pgx pool for the monitoring database, wire it into the
SiteDomainMappingService, and surface its health in /readyz. Point compose
at the dedicated monitoring-postgres service and align local/dev configs
with the per-instance ports. Also reformat the site_domain_mapping types
with gofmt while the files are touched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/ops/repository/site_domain_mapping.go

@@ -32,16 +32,16 @@ type SiteDomainMappingFilter struct {
 
 type CreateSiteDomainMappingInput struct {
 	RegistrableDomain string
-	SiteKey            string
-	SiteName           string
-	IsActive           bool
+	SiteKey           string
+	SiteName          string
+	IsActive          bool
 }
 
 type UpdateSiteDomainMappingInput struct {
 	RegistrableDomain string
-	SiteKey            string
-	SiteName           string
-	IsActive           bool
+	SiteKey           string
+	SiteName          string
+	IsActive          bool
 }
 
 func scanSiteDomainMapping(row pgx.Row) (*domain.SiteDomainMapping, error) {