Web: date picker commits on leave, close day context menu on event click

- Date picker: clicking a day only selects it now; the choice is committed
  when you leave the picker (click outside) or press Save — for both date and
  datetime modes (previously datetime discarded on click-away, and date
  committed instantly on click, neither of which was wanted).
- The day right-click context menu ("Neuen Termin erstellen") now closes when
  an event popup opens (the event row stops propagation, so its own
  outside-click closer never fired).
- version v47 -> v48.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/js/date-picker.js

@@ -48,9 +48,10 @@ export function openDatePicker(anchor, value, mode = 'datetime') {
       resolve(result);
     }
 
-    // Click outside → cancel
+    // Click outside (leaving the picker) → commit the current selection,
+    // rather than discarding it. Cancel button still reverts.
     overlay.addEventListener('mousedown', e => {
-      if (e.target === overlay) done(null);
+      if (e.target === overlay) done(buildResult());
     });
 
     // ── Calendar builder ──────────────────────────────────
@@ -144,13 +145,11 @@ export function openDatePicker(anchor, value, mode = 'datetime') {
         render();
       };
 
-      // Day click
+      // Day click → just select/highlight; committing happens on Save or when
+      // the user leaves the picker (clicks outside).
       card.querySelectorAll('.dtp-day').forEach(el => {
         el.addEventListener('click', () => {
           selDate = new Date(parseInt(el.dataset.ts));
-          // In date-only mode there's nothing else to choose — commit the day
-          // immediately instead of forcing an extra "Save" click.
-          if (mode === 'date') { done(buildResult()); return; }
           if (el.classList.contains('other')) {
             viewYear  = selDate.getFullYear();
             viewMonth = selDate.getMonth();