fix: enable scrolling in CodeEditor widget

Wrap CodeField in SingleChildScrollView with minLines: 1 to prevent
overflow when YAML content exceeds available height.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/shared/components/code_editor/code_editor.dart

@@ -97,9 +97,11 @@ class CodeEditorState extends State<CodeEditor> {
 
     return CodeTheme(
       data: isDark ? _darkTheme(colorScheme) : _lightTheme(colorScheme),
+      child: SingleChildScrollView(
         child: CodeField(
           controller: _controller,
           readOnly: widget.readOnly,
+          minLines: 1,
           gutterStyle: widget.showLineNumbers
               ? GutterStyle(
                   showLineNumbers: true,
@@ -123,6 +125,7 @@ class CodeEditorState extends State<CodeEditor> {
           padding: const EdgeInsets.all(16),
           background: colorScheme.surfaceContainerLowest,
         ),
+      ),
     );
   }