feat: add basic accessibility roles to library components

- NodeEditor: accessible-role list, labeled "Node Editor"
- BaseNode: accessible-role list-item, description indicates selection state
- Pin: accessible-role button, labeled by pin type (input/output)
- Minimal example: sets accessible-label to node title

Enables screen reader support and MCP introspection of the UI tree.

Author: tilladam

examples/minimal/ui/minimal.slint

@@ -21,6 +21,7 @@ export { LinkData, DragState, NodeEditorInternalCallbacks, NodeEditorComputation
 
 component SimpleNode inherits BaseNode {
     in property <string> title: "Node";
+    accessible-label: title;
     // Set node size for BaseNode
     node-width: 250px;
     node-height: 80px;

node-editor-building-blocks.slint

@@ -460,6 +460,10 @@ export component BaseNode inherits Rectangle {
     in property <bool> selected: false;
     in property <length> world-x;
     in property <length> world-y;
+
+    // === Accessibility ===
+    accessible-role: list-item;
+    accessible-description: selected ? "selected" : "";
     // Persistent position offset (survives drag end until model updates)
     property <length> persistent-offset-x: 0px;
     property <length> persistent-offset-y: 0px;
@@ -669,6 +673,10 @@ export component Pin inherits Rectangle {
     in property <int> pin-id;
     in property <int> node-id;  // Node this pin belongs to (for position reporting)
     in property <int> pin-type;  // Type of pin (input/output/custom)
+
+    // === Accessibility ===
+    accessible-role: button;
+    accessible-label: pin-type == 1 ? "input pin" : pin-type == 2 ? "output pin" : "pin";
     in property <color> base-color: #888888;
     in property <color> hover-color: #aaaaaa;
     in property <length> base-size: 12px;

node-editor.slint

@@ -84,6 +84,10 @@ export enum BoxSelectionModifier {
 /// Multiple editors in separate windows work fine. This limitation will be
 /// lifted once Slint introduces component-scoped globals.
 export component NodeEditor inherits FocusScope {
+    // === Accessibility ===
+    accessible-role: list;
+    accessible-label: "Node Editor";
+
     // === Shared viewport state ===
     in-out property <length> pan-x: 0px;
     in-out property <length> pan-y: 0px;