feat: add scrollable UI transform and UiScrollResult

proto/decentraland/sdk/components/ui_scroll_result.proto

@@ -0,0 +1,12 @@
+syntax = "proto3";
+
+package decentraland.sdk.components;
+
+import "decentraland/sdk/components/common/id.proto";
+import "decentraland/common/vectors.proto";
+
+option (common.ecs_component_id) = 1202;
+
+message PBUiScrollResult {
+  decentraland.common.Vector2 value = 1;
+}

proto/decentraland/sdk/components/ui_transform.proto

@@ -4,6 +4,7 @@ package decentraland.sdk.components;
 
 import "decentraland/sdk/components/common/id.proto";
 import "decentraland/common/colors.proto";
+import "decentraland/common/vectors.proto";
 
 option (common.ecs_component_id) = 1050;
 
@@ -80,6 +81,20 @@ enum PointerFilterMode {
   PFM_BLOCK = 1;
 }
 
+enum ShowScrollBar {
+  SSB_BOTH = 0;
+  SSB_ONLY_VERTICAL = 1;
+  SSB_ONLY_HORIZONTAL = 2;
+  SSB_HIDDEN = 3;
+}
+
+message ScrollPositionValue {
+  oneof value {
+    decentraland.common.Vector2 position = 1;
+    string reference = 2;
+  }
+}
+
 message PBUiTransform {
   int32 parent = 1;
   int32 right_of = 2;
@@ -174,5 +189,22 @@ message PBUiTransform {
   optional decentraland.common.Color4 border_right_color = 72;
 
   optional float opacity = 73; // default: 1
+
+  // Unique name for this UI element (HTML-`id`-like). Registered in a
+  // named-element table so other components/RPCs can refer to it: today
+  // consumed by ScrollPositionValue.reference (scroll a named child into view)
+  // and the UI focus RPC. default empty
+  optional string element_id = 74;
+
+  // Scroll offset for this node's scroll viewport (only meaningful when
+  // overflow = YGO_SCROLL). Either a literal Vector2 position, or a string
+  // referencing another element's element_id to scroll into view.
+  // default position=(0,0)
+  optional ScrollPositionValue scroll_position = 75;
+
+  // Which scroll bars to render when this node is scrollable.
+  // default ShowScrollBar.SSB_BOTH
+  optional ShowScrollBar scroll_visible = 76;
+
   optional int32 z_index = 77; // default: 0 — controls render stacking order. Higher values appear in front of lower values.
 }