feat: introduce Radix UI design system skill with a component template and examples.

skills/radix-ui-design-system/examples/dropdown-example.tsx

@@ -0,0 +1,162 @@
+import * as DropdownMenu from '@radix-ui/react-dropdown-menu';
+import {
+  HamburgerMenuIcon,
+  DotFilledIcon,
+  CheckIcon,
+  ChevronRightIcon,
+} from '@radix-ui/react-icons';
+import './dropdown.css';
+
+/**
+ * Example: Complete Dropdown Menu
+ * 
+ * Features:
+ * - Items, separators, labels
+ * - Checkbox items
+ * - Radio group items
+ * - Sub-menus
+ * - Keyboard navigation
+ */
+export function CompleteDropdown() {
+  const [bookmarksChecked, setBookmarksChecked] = React.useState(true);
+  const [urlsChecked, setUrlsChecked] = React.useState(false);
+  const [person, setPerson] = React.useState('pedro');
+
+  return (
+    <DropdownMenu.Root>
+      <DropdownMenu.Trigger asChild>
+        <button className="icon-button" aria-label="Customise options">
+          <HamburgerMenuIcon />
+        </button>
+      </DropdownMenu.Trigger>
+
+      <DropdownMenu.Portal>
+        <DropdownMenu.Content className="dropdown-content" sideOffset={5}>
+          {/* Regular items */}
+          <DropdownMenu.Item className="dropdown-item">
+            New Tab <div className="right-slot">⌘+T</div>
+          </DropdownMenu.Item>
+          <DropdownMenu.Item className="dropdown-item">
+            New Window <div className="right-slot">⌘+N</div>
+          </DropdownMenu.Item>
+          <DropdownMenu.Item className="dropdown-item" disabled>
+            New Private Window <div className="right-slot">⇧+⌘+N</div>
+          </DropdownMenu.Item>
+
+          {/* Sub-menu */}
+          <DropdownMenu.Sub>
+            <DropdownMenu.SubTrigger className="dropdown-subtrigger">
+              More Tools
+              <div className="right-slot">
+                <ChevronRightIcon />
+              </div>
+            </DropdownMenu.SubTrigger>
+            <DropdownMenu.Portal>
+              <DropdownMenu.SubContent
+                className="dropdown-subcontent"
+                sideOffset={2}
+                alignOffset={-5}
+              >
+                <DropdownMenu.Item className="dropdown-item">
+                  Save Page As… <div className="right-slot">⌘+S</div>
+                </DropdownMenu.Item>
+                <DropdownMenu.Item className="dropdown-item">
+                  Create Shortcut…
+                </DropdownMenu.Item>
+                <DropdownMenu.Item className="dropdown-item">
+                  Name Window…
+                </DropdownMenu.Item>
+                <DropdownMenu.Separator className="dropdown-separator" />
+                <DropdownMenu.Item className="dropdown-item">
+                  Developer Tools
+                </DropdownMenu.Item>
+              </DropdownMenu.SubContent>
+            </DropdownMenu.Portal>
+          </DropdownMenu.Sub>
+
+          <DropdownMenu.Separator className="dropdown-separator" />
+
+          {/* Checkbox items */}
+          <DropdownMenu.CheckboxItem
+            className="dropdown-checkbox-item"
+            checked={bookmarksChecked}
+            onCheckedChange={setBookmarksChecked}
+          >
+            <DropdownMenu.ItemIndicator className="dropdown-item-indicator">
+              <CheckIcon />
+            </DropdownMenu.ItemIndicator>
+            Show Bookmarks <div className="right-slot">⌘+B</div>
+          </DropdownMenu.CheckboxItem>
+          <DropdownMenu.CheckboxItem
+            className="dropdown-checkbox-item"
+            checked={urlsChecked}
+            onCheckedChange={setUrlsChecked}
+          >
+            <DropdownMenu.ItemIndicator className="dropdown-item-indicator">
+              <CheckIcon />
+            </DropdownMenu.ItemIndicator>
+            Show Full URLs
+          </DropdownMenu.CheckboxItem>
+
+          <DropdownMenu.Separator className="dropdown-separator" />
+
+          {/* Radio group */}
+          <DropdownMenu.Label className="dropdown-label">
+            People
+          </DropdownMenu.Label>
+          <DropdownMenu.RadioGroup value={person} onValueChange={setPerson}>
+            <DropdownMenu.RadioItem className="dropdown-radio-item" value="pedro">
+              <DropdownMenu.ItemIndicator className="dropdown-item-indicator">
+                <DotFilledIcon />
+              </DropdownMenu.ItemIndicator>
+              Pedro Duarte
+            </DropdownMenu.RadioItem>
+            <DropdownMenu.RadioItem className="dropdown-radio-item" value="colm">
+              <DropdownMenu.ItemIndicator className="dropdown-item-indicator">
+                <DotFilledIcon />
+              </DropdownMenu.ItemIndicator>
+              Colm Tuite
+            </DropdownMenu.RadioItem>
+          </DropdownMenu.RadioGroup>
+
+          <DropdownMenu.Arrow className="dropdown-arrow" />
+        </DropdownMenu.Content>
+      </DropdownMenu.Portal>
+    </DropdownMenu.Root>
+  );
+}
+
+/**
+ * Example: Simple Actions Menu
+ * 
+ * Common use case for data tables, cards, etc.
+ */
+export function ActionsMenu({ onEdit, onDuplicate, onDelete }) {
+  return (
+    <DropdownMenu.Root>
+      <DropdownMenu.Trigger asChild>
+        <button className="icon-button" aria-label="Actions">
+          <DotsHorizontalIcon />
+        </button>
+      </DropdownMenu.Trigger>
+
+      <DropdownMenu.Portal>
+        <DropdownMenu.Content className="dropdown-content" align="end">
+          <DropdownMenu.Item className="dropdown-item" onSelect={onEdit}>
+            Edit
+          </DropdownMenu.Item>
+          <DropdownMenu.Item className="dropdown-item" onSelect={onDuplicate}>
+            Duplicate
+          </DropdownMenu.Item>
+          <DropdownMenu.Separator className="dropdown-separator" />
+          <DropdownMenu.Item
+            className="dropdown-item dropdown-item-danger"
+            onSelect={onDelete}
+          >
+            Delete
+          </DropdownMenu.Item>
+        </DropdownMenu.Content>
+      </DropdownMenu.Portal>
+    </DropdownMenu.Root>
+  );
+}