feat(editor): Shiki syntax highlighting in the file editor (CodeMirror)

Bring the CodeMirror file editor up to the same rich highlighting as the Shiki
file view, so toggling edit <-> view is visually consistent. lezer collapses far
more tokens than TextMate (import/from/const are all "keyword"), so a theme
remap can't reach parity — instead, project real Shiki tokens onto decorations.

- Worker: add highlightTokens — tokenize with an arbitrary registered TextMate
  theme and return per-line styled runs with offsets. The theme object ships to
  the worker once per name; later calls send only the name.
- New shikiHighlight CodeMirror extension: a StateField of mark decorations
  built from worker tokens. Re-tokenizes on a short idle (off the keystroke
  path) and maps decorations through edits so colors persist while typing.
- flexokiTheme: add { syntaxColors: false } to keep only the editor UI theme,
  so the lezer highlighter doesn't compete with the Shiki decorations.
- FilesView: enable Shiki highlighting (same language resolver as the file view
  → identical language) and drop lezer token colors when it's active. lezer
  language stays on for indentation/folding/brackets.

packages/ui/src/components/views/FilesView.tsx

@@ -29,6 +29,8 @@ import { JsonTreeView } from '@/components/ui/JsonTreeView';
 import { SimpleMarkdownRenderer } from '@/components/chat/MarkdownRenderer';
 import { languageByExtension, loadLanguageByExtension } from '@/lib/codemirror/languageByExtension';
 import { createFlexokiCodeMirrorTheme } from '@/lib/codemirror/flexokiTheme';
+import { shikiHighlightExtension } from '@/lib/codemirror/shikiHighlight';
+import { getResolvedShikiTheme } from '@/lib/shiki/appThemeRegistry';
 import { File as PierreFile } from '@pierre/diffs/react';
 import {
   Dialog,
@@ -2824,11 +2826,23 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
       return [createFlexokiCodeMirrorTheme(currentTheme)];
     }
 
-    const extensions = [createFlexokiCodeMirrorTheme(currentTheme)];
+    // Shiki token colors (worker-backed) match the Shiki file view exactly.
+    // Same language resolver as the view, so both agree on the language. When
+    // Shiki is the color source, drop the lezer token colors to avoid a
+    // competing highlighter (keep the lezer language for indentation/folding).
+    const shikiLanguage = getLanguageFromExtension(selectedFile.path);
+    const extensions = [createFlexokiCodeMirrorTheme(currentTheme, shikiLanguage ? { syntaxColors: false } : undefined)];
     const language = staticLanguageExtension ?? dynamicLanguageExtension;
     if (language) {
       extensions.push(language);
     }
+    if (shikiLanguage) {
+      extensions.push(shikiHighlightExtension({
+        language: shikiLanguage,
+        themeName: currentTheme.metadata.id,
+        theme: getResolvedShikiTheme(currentTheme),
+      }));
+    }
     if (wrapLines) {
       extensions.push(EditorView.lineWrapping);
     }
@@ -2939,7 +2953,7 @@ export const FilesView: React.FC<FilesViewProps> = ({ mode = 'full' }) => {
   }, [pdfAssetAuthKey, t]);
 
   const isPdfAssetAuthLoading = Boolean(pdfAssetAuthKey && pdfAssetAuthReadyKey !== pdfAssetAuthKey);
-
+
   const imageSrc = selectedFile?.path && isSelectedImage
     ? (runtime.isDesktop
       ? (isSelectedSvg