chore(test): clean up unused code and fix test helper usage

- Update TestBatchBindings_Status to use newTestHandlerWithRedis helper
- Remove unused jsonID helper function from sync_bindings_spec_test.go
- Add time import to models.go

internal/service/sync_bindings_spec_test.go

@@ -2,7 +2,6 @@ package service
 
 import (
 	"encoding/json"
-	"strconv"
 	"testing"
 
 	"github.com/alicebob/miniredis/v2"
@@ -139,7 +138,3 @@ func TestSyncBindings_SelectorRegexAndNormalize(t *testing.T) {
 		t.Fatalf("expected config_error with no upstreams, got %+v", snapNorm.Candidates[0])
 	}
 }
-
-func jsonID(id uint) string {
-	return strconv.FormatUint(uint64(id), 10)
-}