feat: add CodeMirror-based code editor component and routing setup

- Implemented CodeEditor component using CodeMirror for JavaScript editing.
- Added global styles in index.css for consistent UI.
- Set up routing with TanStack Router, including root and nested routes.
- Created About, C, and Editor routes with respective components.
- Integrated CodeEditor into the Editor route for code editing functionality.
- Configured TypeScript settings in tsconfig.json for strict type checking.
- Established Vite configuration for React and TanStack Router integration.

src/components/CodeEditor.tsx

@@ -0,0 +1,27 @@
+import CodeMirror from '@uiw/react-codemirror'
+import { javascript } from '@codemirror/lang-javascript'
+import { useState } from 'react'
+
+interface CodeEditorProps {
+  initialValue?: string
+  onChange?: (value: string) => void
+}
+
+export function CodeEditor({ initialValue = '', onChange }: CodeEditorProps) {
+  const [value, setValue] = useState(initialValue)
+
+  const handleChange = (val: string) => {
+    setValue(val)
+    onChange?.(val)
+  }
+
+  return (
+    <CodeMirror
+      value={value}
+      height="500px"
+      extensions={[javascript()]}
+      onChange={handleChange}
+      theme="dark"
+    />
+  )
+}