Fix paywall colors in light mode.

Use theme-aware paywall panel background instead of hard-coded black.

Co-authored-by: Cursor <cursoragent@cursor.com>

zoom_app/ViewController.swift

@@ -3696,7 +3696,8 @@ class ViewController: NSViewController {
         let panel = NSView()
         panel.translatesAutoresizingMaskIntoConstraints = false
         panel.wantsLayer = true
-        panel.layer?.backgroundColor = NSColor.black.cgColor
+        // Theme-aware surface so Light Mode doesn't render on a black backdrop.
+        panel.layer?.backgroundColor = palette.appBackground.cgColor
         panel.layer?.cornerRadius = 0
         styleSurface(panel, borderColor: NSColor.clear, borderWidth: 0, shadow: false)
         root.addSubview(panel)