Scale the interface fractionally on Linux

Java2D on X11 (and so under XWayland) truncates its scale to a whole
number, drawing 150 % at 100 %. On Linux, pin Java2D to 1 and hand the
full factor to FlatLaf, taken from XSETTINGS Xft/DPI, KWin's Xwayland
scale or GDK_SCALE, or chosen in Options → Design.

The client's own sizes now go through UIScale: borders, gaps, dialog and
row sizes, icons (rendered at the scaled size, so they stay crisp),
custom-painted components and font sizes in the HTML views.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ts3-client/swing/src/main/java/com/ts3client/ui/StatusBar.java

@@ -1,6 +1,7 @@
 package com.ts3client.ui;
 
-import javax.swing.BorderFactory;
+import com.formdev.flatlaf.util.ScaledEmptyBorder;
+
 import javax.swing.JLabel;
 import javax.swing.JPanel;
 import java.awt.BorderLayout;
@@ -14,7 +15,7 @@ final class StatusBar extends JPanel {
     StatusBar() {
         super(new BorderLayout());
         setBackground(Theme.statusBg());
-        setBorder(BorderFactory.createEmptyBorder(3, 8, 3, 8));
+        setBorder(new ScaledEmptyBorder(3, 8, 3, 8));
         statusLabel.setFont(Theme.uiFont());
         codecLabel.setFont(Theme.uiFont());
         codecLabel.setForeground(Theme.chatSystem());