feat: enhance day detail panel functionality and user experience

- Added functionality to lock the background scroll when the day detail panel is open, improving user interaction by preventing background movement.
- Implemented logic to restore the scroll position when the panel is closed, ensuring a seamless user experience.
- Updated CSS to support the new behavior, enhancing the visual consistency of the day detail panel.
- Added early return checks in navigation button event listeners to prevent actions while the day detail panel is open, improving performance and usability.

webapp/js/main.js

@@ -178,6 +178,7 @@ async function loadMonth() {
 
 if (prevBtn) {
   prevBtn.addEventListener("click", () => {
+    if (document.body.classList.contains("day-detail-sheet-open")) return;
     if (accessDeniedEl && !accessDeniedEl.hidden) return;
     state.current.setMonth(state.current.getMonth() - 1);
     loadMonth();
@@ -185,6 +186,7 @@ if (prevBtn) {
 }
 if (nextBtn) {
   nextBtn.addEventListener("click", () => {
+    if (document.body.classList.contains("day-detail-sheet-open")) return;
     if (accessDeniedEl && !accessDeniedEl.hidden) return;
     state.current.setMonth(state.current.getMonth() + 1);
     loadMonth();
@@ -211,6 +213,7 @@ if (nextBtn) {
     "touchend",
     (e) => {
       if (e.changedTouches.length === 0) return;
+      if (document.body.classList.contains("day-detail-sheet-open")) return;
       if (accessDeniedEl && !accessDeniedEl.hidden) return;
       const t = e.changedTouches[0];
       const deltaX = t.clientX - startX;