Add safe text editing to preview window

server/public/styles.css

@@ -1264,6 +1264,27 @@
   padding-bottom: 6px;
 }
 
+.u-nav .preview-actions {
+  align-items: center;
+  display: flex;
+  gap: 6px;
+  justify-content: flex-end;
+  white-space: nowrap;
+}
+
+.u-nav .preview-actions button {
+  align-items: center;
+  display: inline-flex;
+  font-size: 12px;
+  gap: 5px;
+  min-height: 28px;
+}
+
+.u-nav .preview-actions .unav-icon {
+  height: 14px;
+  width: 14px;
+}
+
 .u-nav .preview-nav {
   display: inline-flex;
   gap: 4px;
@@ -1295,6 +1316,27 @@
   white-space: pre;
 }
 
+.u-nav .preview-editor {
+  background: var(--surface-2);
+  border: 1px solid var(--accent);
+  border-radius: 7px;
+  color: var(--text);
+  font: 12px/1.45 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
+  margin: 0;
+  min-height: 0;
+  outline: 0;
+  overflow: auto;
+  padding: 10px;
+  resize: none;
+  tab-size: 2;
+  white-space: pre;
+  width: 100%;
+}
+
+.u-nav .preview-editor:focus {
+  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--accent) 45%, transparent);
+}
+
 .u-nav .preview-rendered,
 .u-nav .preview-table-wrap,
 .u-nav .preview-media,