fix(services): Fix duplicate health registry provider

- Change from fx.Provide to fx.Invoke for health registry registration
  - CoreModule() already provides *health.Registry
  - Services should register their database checkers with the existing registry
  - Use fx.Invoke to register database health checkers instead of providing new registry

- Fixes duplicate provider error for *health.Registry
- All services now build and should start successfully

cmd/identity-service/main.go

@@ -107,11 +107,9 @@ func main() {
 			return client, nil
 		}),
 
-		// Health registry with database checker
-		fx.Provide(func(db *database.Client, log logger.Logger) (*healthpkg.Registry, error) {
-			registry := healthpkg.NewRegistry()
+		// Register database health checker with existing health registry
+		fx.Invoke(func(registry *healthpkg.Registry, db *database.Client) {
 			registry.Register("database", healthpkg.NewDatabaseChecker(db))
-			return registry, nil
 		}),
 
 		// Provide identity service and gRPC server (defined in identity_service_fx.go)