update widgets, add copy paste buffer

src/ui/ui_widgets.h

@@ -13,6 +13,7 @@
 // Widget state (global, managed by widget layer)
 
 #define UI_WIDGET_MAX_DROPDOWN_ITEMS 32
+#define UI_WIDGET_MAX_TEXT_INPUTS    16
 
 struct UI_WidgetState {
     // Text input focus
@@ -20,6 +21,15 @@ struct UI_WidgetState {
     int32_t  cursor_pos;       // Cursor position in focused text input
     F32      cursor_blink;     // Blink timer (seconds)
 
+    // Text selection (sel_start == sel_end means no selection)
+    int32_t  sel_start;        // Selection anchor (where selection began)
+    int32_t  sel_end;          // Selection extent (moves with cursor)
+
+    // Tab cycling: registered text input IDs in order of declaration
+    uint32_t text_input_ids[UI_WIDGET_MAX_TEXT_INPUTS];
+    int32_t  text_input_count;
+    B32      tab_pressed;      // True on the frame Tab was pressed
+
     // Dropdown
     uint32_t open_dropdown_id; // Clay element ID hash of the open dropdown (0 = none)