Improve non-premium overlay readability in light mode.

Use a dark text color for the locked events message in light mode while preserving white text in dark mode so the premium prompt remains clearly visible.

Made-with: Cursor

meetings_app/ViewController.swift

@@ -2799,7 +2799,7 @@ private extension ViewController {
             lockOverlay.layer?.masksToBounds = true
             lockOverlay.layer?.backgroundColor = NSColor.black.withAlphaComponent(darkModeEnabled ? 0.28 : 0.12).cgColor
 
-            let lockLabel = textLabel("Get Premium to see events", font: NSFont.systemFont(ofSize: 12, weight: .semibold), color: .white)
+            let lockLabel = textLabel("Get Premium to see events", font: NSFont.systemFont(ofSize: 12, weight: .semibold), color: darkModeEnabled ? .white : .black)
             lockLabel.alignment = .center
 
             card.addSubview(lockOverlay)