Update editor styles for CodeMirror integration

src/index.css

@@ -624,59 +624,45 @@ body:not([data-theme="light"]) .folder-item {
   justify-content: flex-end;
 }
 
-.editor__textarea {
+.editor__codemirror {
   flex: 1;
   width: 100%;
-  resize: none;
-  border: none;
-  padding: 14px;
-  font-family: "SF Mono", "Menlo", "Consolas", monospace;
-  font-size: 0.95rem;
-  line-height: 1.5;
-  white-space: pre-wrap;
-  word-break: break-word;
-  overflow-wrap: anywhere;
+  min-height: 0;
+}
+
+.editor__codemirror--hidden {
+  display: none;
+}
+
+.editor__codemirror .cm-editor {
+  height: 100%;
   background: transparent;
   color: var(--ink);
-}
-
-.editor__textarea:focus {
-  outline: none;
-}
-
-.editor__textarea--hidden {
-  display: none;
-}
-
-.editor__textarea-wrap--preview .tln-wrapper {
-  display: none;
-}
-
-.tln-wrapper {
-  padding: 14px 10px;
-  min-width: 3ch;
-  text-align: right;
   font-family: "SF Mono", "Menlo", "Consolas", monospace;
   font-size: 0.95rem;
   line-height: 1.5;
-  color: var(--muted);
+}
+
+.editor__codemirror .cm-scroller {
+  overflow: auto;
+}
+
+.editor__codemirror .cm-content {
+  padding: 14px;
+}
+
+.editor__codemirror .cm-gutters {
   background: var(--bg-contrast);
   border-right: 1px solid var(--border);
-  user-select: none;
-  overflow: hidden;
-  height: 100%;
-  counter-reset: line;
+  color: var(--muted);
 }
 
-.tln-line {
-  display: block;
-  height: 1.5em;
+.editor__codemirror .cm-gutterElement {
+  padding: 0 10px 0 0;
 }
 
-.tln-line::before {
-  counter-increment: line;
-  content: counter(line);
-  font-variant-numeric: tabular-nums;
+.editor__codemirror .cm-activeLineGutter {
+  background: transparent;
 }
 
 .markdown-preview {