Fix rect selection in table view: prevent native text drag/selection

Added user-select:none and -webkit-user-drag:none to #entriesContainer.
Also added a dragstart listener that prevents default for any element
that is not [draggable='true'], stopping the browser from creating drag
ghosts of selected table text/headers during rectangle selection.

js/app.js

@@ -1141,6 +1141,11 @@ if (token && curUser) {
     }
 })();
 
+// Prevent native drag on non-card elements (table headers, text, etc.)
+document.getElementById('entriesContainer').addEventListener('dragstart', function(e) {
+    if (!e.target?.closest?.('[draggable="true"]')) e.preventDefault();
+});
+
 // Document mousedown: rect selection on vault background, clear outside vault
 document.addEventListener('mousedown', function(e) {
     if (e.button !== 0 || rectState.active) return;