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/SettingsDialog.java

@@ -1,5 +1,6 @@
 package com.ts3client.ui;
 
+import com.formdev.flatlaf.util.UIScale;
 import com.ts3client.audio.OpusParameters;
 import com.ts3client.audio.VoiceInput;
 import com.ts3client.audio.VoiceOutput;
@@ -92,8 +93,8 @@ public final class SettingsDialog extends JDialog {
         });
 
         pack();
-        setSize(new Dimension(480, 540));
-        setMinimumSize(new Dimension(420, 360));
+        setSize(UIScale.scale(new Dimension(480, 540)));
+        setMinimumSize(UIScale.scale(new Dimension(420, 360)));
         setLocationRelativeTo(owner);
     }