feat: Refactor example page and showcase components

- Updated ExamplePage to use a single Showcase component instead of separate InputShowCase and FormShowcase components.
- Added CheckboxShowcase, FormShowcase, and InputShowCase components to the showcase directory.
- Implemented Checkbox component with various states and styles.
- Enhanced InputShowCase to demonstrate different input types and states.
- Integrated new styles for checkbox variants and states.
- Updated package dependencies to include @rc-component/checkbox.

pnpm-lock.yaml

@@ -158,6 +158,9 @@ importers:
 
   packages/ui:
     dependencies:
+      '@rc-component/checkbox':
+        specifier: ^1.0.1
+        version: 1.0.1(react-dom@19.2.3)(react@19.2.3)
       '@rc-component/form':
         specifier: ^1.6.2
         version: 1.6.2(react-dom@19.2.3)(react@19.2.3)
@@ -1145,6 +1148,18 @@ packages:
       '@babel/runtime': 7.28.4
     dev: false
 
+  /@rc-component/checkbox@1.0.1(react-dom@19.2.3)(react@19.2.3):
+    resolution: {integrity: sha512-08yTH8m+bSm8TOqbybbJ9KiAuIATti6bDs2mVeSfu4QfEnyeF6X0enHVvD1NEAyuBWEAo56QtLe++MYs2D9XiQ==}
+    peerDependencies:
+      react: '>=16.9.0'
+      react-dom: '>=16.9.0'
+    dependencies:
+      '@rc-component/util': 1.7.0(react-dom@19.2.3)(react@19.2.3)
+      clsx: 2.1.1
+      react: 19.2.3
+      react-dom: 19.2.3(react@19.2.3)
+    dev: false
+
   /@rc-component/form@1.6.2(react-dom@19.2.3)(react@19.2.3):
     resolution: {integrity: sha512-OgIn2RAoaSBqaIgzJf/X6iflIa9LpTozci1lagLBdURDFhGA370v0+T0tXxOi8YShMjTha531sFhwtnrv+EJaQ==}
     engines: {node: '>=8.x'}