feat: capture caret/scroll in editor autosave

openspec/changes/sidepanel-ux-improvements/tasks.md

@@ -7,7 +7,7 @@
 
 ## 2. Caret persistence in the side panel
 
-- [ ] 2.1 In `sidepanel/sidepanel.js`, pass current caret (`selectionStart`/`selectionEnd`) and `scrollTop` to `saveNote` in the existing autosave (`doSave`)
+- [x] 2.1 In `sidepanel/sidepanel.js`, pass current caret (`selectionStart`/`selectionEnd`) and `scrollTop` to `saveNote` in the existing autosave (`doSave`)
 - [ ] 2.2 Track caret-only movement via `document` `selectionchange` (filtered to the editor) and editor `scroll`; debounce ~800ms into a caret-only save that calls `saveNote` without broadcasting; skip it while a content autosave is pending
 - [ ] 2.3 Flush any pending caret-only save on editor `blur` and on `visibilitychange` → hidden
 

sidepanel/sidepanel.js

@@ -127,7 +127,11 @@ async function doSave() {
       favIconUrl: tab.favIconUrl || '',
     };
 
-    const saved = await saveNote(currentKey, editor.value, pageMeta);
+    const saved = await saveNote(currentKey, editor.value, pageMeta, {
+      caretStart: editor.selectionStart,
+      caretEnd: editor.selectionEnd,
+      scrollTop: editor.scrollTop,
+    });
     currentNote = saved;
     updateStatus('Saved');