fix: UI redesign — horizontal instance rows, proper scaling, readable tag cards

- Backend: add replicas field to InstanceResponse (extracted from values.replicaCount)
- InstanceCard: complete redesign as horizontal row layout
  - Status bar | Name+Chart | Replicas +/- | Action buttons
  - Scale controls show for deployed AND failed statuses (scale to 0)
  - Fix replicas display using new instance.replicas backend field
- InstancesManagementPage: vertical row list + onScale callback to update state
- TagCard: restore proper padding (p-4), min-width, readable button sizes
- ArtifactBrowserPage: reduce grid density (sm:1 md:2 lg:3)
- ModifyModal: simplify to YAML-only editing with current values pre-populated
  - Remove schema-based form generator
  - Keep values-diff as collapsible reference panel

backend/internal/adapter/input/http/dto/instance_dto.go

@@ -73,6 +73,7 @@ type InstanceResponse struct {
 	LastError      string                 `json:"lastError,omitempty"`
 	Revision       int                    `json:"revision"`
 	Values         map[string]interface{} `json:"values,omitempty"`
+	Replicas       int                    `json:"replicas"`
 	CreatedAt      string                 `json:"createdAt"`
 	UpdatedAt      string                 `json:"updatedAt"`
 }

backend/internal/adapter/input/http/rest/instance_handler.go

@@ -566,6 +566,17 @@ func formatTime(value time.Time) string {
 }
 
 func convertInstanceResponse(instance *entity.Instance, includeValues bool) *dto.InstanceResponse {
+	replicas := 0
+	if v, ok := instance.Values["replicaCount"]; ok {
+		switch n := v.(type) {
+		case float64:
+			replicas = int(n)
+		case int:
+			replicas = n
+		case int64:
+			replicas = int(n)
+		}
+	}
 	response := &dto.InstanceResponse{
 		ID:             instance.ID,
 		ClusterID:      instance.ClusterID,
@@ -583,6 +594,7 @@ func convertInstanceResponse(instance *entity.Instance, includeValues bool) *dto
 		LastOperation:  string(instance.LastOperation),
 		LastError:      instance.LastError,
 		Revision:       instance.Revision,
+		Replicas:       replicas,
 		AllowedActions: []string{"view", "update", "delete"},
 		CreatedAt:      instance.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
 		UpdatedAt:      instance.UpdatedAt.Format("2006-01-02T15:04:05Z07:00"),