Fix editor not rendering on every other source mode switch

src/lib/components/Editor.svelte

@@ -3392,7 +3392,15 @@
 
 	function createEditor(content: string) {
 		if (!editorElement) return;
-		destroyEditor();
+		// Don't call destroyEditor here — it sets editorReady=false which
+		// triggers reactivity and races with the tick().then() in the
+		// source-mode swap. Just destroy the editor instance directly.
+		if (editor) {
+			editor.destroy();
+			editor = null;
+		}
+		mathObserver?.disconnect();
+		mathObserver = null;
 
 		isLargeDoc = content.length > LARGE_DOC_CHARS;
 		const html = markdownToHtml(content);
@@ -4616,11 +4624,6 @@
 		// Only act if we have a loaded note
 		if (!loadedPath) return;
 
-		// untrack: prevent flushSave() (inside destroyEditor) from adding
-		// $editorDirty/$activeNote as effect dependencies, which causes
-		// the effect to re-run and race with tick().then() — resulting in
-		// the editor failing to render on every other source-mode switch.
-		untrack(() => {
 		if (isSource && !lastSourceMode) {
 			// Switching TO source: extract markdown from editor
 			sourceContent = editor ? editorToMarkdown() : ($activeNote?.content ?? '');
@@ -4647,7 +4650,6 @@
 			}
 		}
 	});
-	});
 
 	// Tauri drag-drop listener for OS file drops (browser DragEvent doesn't have files in Tauri)
 	let unlistenDragDrop: (() => void) | null = null;