fix: event popup — allow toolbar button clicks and text selection while draggable

- Don't start a header drag when the pointer goes down on a button/link, so
  edit/copy/delete/close work again
- Make the popup body text selectable (user-select: text) for copying

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

frontend/css/app.css

@@ -1198,7 +1198,7 @@ a { color: var(--primary); text-decoration: none; }
 }
 .popup-icon-btn:active { transform: scale(.88); }
 
-.popup-body { padding: 12px 16px 14px; display: flex; flex-direction: column; gap: 9px; }
+.popup-body { padding: 12px 16px 14px; display: flex; flex-direction: column; gap: 9px; -webkit-user-select: text; user-select: text; }
 .popup-row { display: flex; align-items: flex-start; gap: 10px; font-size: 13px; line-height: 1.45; color: var(--text-2); }
 .popup-row-icon { width: 16px; height: 16px; flex-shrink: 0; margin-top: 1px; fill: var(--text-3); }
 #popup-time { color: var(--text-1); font-weight: 500; }

frontend/js/calendar.js

@@ -1465,6 +1465,9 @@ function showEventPopup(ev, anchor) {
   };
   dragHandle.onpointerdown = e => {
     if (e.button !== 0) return;
+    // Let the toolbar buttons (edit/copy/delete/close) receive their click —
+    // only the bare header area starts a drag.
+    if (e.target.closest('button, a')) return;
     dragOffX = e.clientX - popup.getBoundingClientRect().left;
     dragOffY = e.clientY - popup.getBoundingClientRect().top;
     dragHandle.setPointerCapture(e.pointerId);