fix: resolve CodeMirror dark mode and theme switching issues (#138)

* fix: improve CodeMirror dark mode theme detection and system theme support

- Use resolvedTheme from next-themes for better theme resolution
- Add fallback to system preference detection during initialization
- Add dedicated effect to handle initial theme resolution
- Remove duplicate theme update logic
- Fix theme switching when system mode changes

This ensures the code editor properly matches the system dark mode
and responds correctly to theme changes.

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

Co-Authored-By: Claude <claude@ghostpaste.dev>

* fix: resolve CodeMirror theme switching issue

Remove duplicate theme update effect that was interfering with
proper theme switching. Now the editor correctly responds to
manual theme changes while still supporting system theme detection.

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

Co-Authored-By: Claude <claude@ghostpaste.dev>

* fix: improve CodeMirror dark mode theme detection and system theme support

- Use resolvedTheme from next-themes for better theme resolution
- Add fallback to system preference detection during initialization
- Add dedicated effect to handle initial theme resolution
- Remove duplicate theme update logic
- Fix theme switching when system mode changes

This ensures the code editor properly matches the system dark mode
and responds correctly to theme changes.

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

Co-Authored-By: Claude <claude@ghostpaste.dev>

* fix: resolve CodeMirror theme switching issue

Remove duplicate theme update effect that was interfering with
proper theme switching. Now the editor correctly responds to
manual theme changes while still supporting system theme detection.

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

Co-Authored-By: Claude <claude@ghostpaste.dev>

---------

Co-authored-by: Claude <claude@ghostpaste.dev>

Author: nullcoder

components/ui/code-editor.tsx

@@ -113,7 +113,7 @@ export const CodeEditor = forwardRef<CodeEditorHandle, CodeEditorProps>(
   ) {
     const containerRef = useRef<HTMLDivElement>(null);
     const viewRef = useRef<EditorView | null>(null);
-    const { theme: systemTheme } = useTheme();
+    const { resolvedTheme } = useTheme();
 
     // Store the onChange callback in a ref to avoid stale closures
     const onChangeRef = useRef(onChange);
@@ -139,8 +139,8 @@ export const CodeEditor = forwardRef<CodeEditorHandle, CodeEditorProps>(
       []
     );
 
-    // Determine the active theme
-    const activeTheme = themeOverride || systemTheme || "light";
+    // Determine the active theme - use resolvedTheme which handles system theme properly
+    const activeTheme = themeOverride || resolvedTheme || "light";
 
     // Get language extension
     const getLanguageExtension = useCallback((lang: string) => {
@@ -215,11 +215,19 @@ export const CodeEditor = forwardRef<CodeEditorHandle, CodeEditorProps>(
       // Debounced onChange for performance
       let changeTimeout: ReturnType<typeof setTimeout>;
 
+      // Determine theme for initialization - prefer resolved theme but fallback to system preference
+      const initTheme =
+        resolvedTheme ||
+        (typeof window !== "undefined" &&
+        window.matchMedia("(prefers-color-scheme: dark)").matches
+          ? "dark"
+          : "light");
+
       // Create extensions with compartments
       const extensions = [
         ...baseExtensions,
         languageCompartment.of(getLanguageExtension(language)),
-        themeCompartment.of(getThemeExtension(activeTheme)),
+        themeCompartment.of(getThemeExtension(initTheme)),
         readOnlyCompartment.of(EditorState.readOnly.of(readOnly)),
         lineNumbersCompartment.of(
           showLineNumbers ? [lineNumbers(), foldGutter()] : []