Theme-linked glow and terminal, tabs, fonts and layout tweaks

- Real window glow (decoration.glow) plus borders and tab bar take their
  colours from DMS (hypr/dms/colors.lua); Hyprland reloads when DMS changes
  the theme.
- kitty: colours and tab colours come from DMS (dank-theme/dank-tabs),
  no more hard-coded palette.
- Group (tab) mode: Mod+W tabs the whole workspace, thinner tab bar.
- Fullscreen programs keep the DMS bar (Mod+F maximizes, Mod+Shift+F is real
  fullscreen); per-monitor workspace switching on Mod+Tab.
- Less jelly animations, smaller gaps, weaker glow.
- JetBrains Mono is the default monospace font (fontconfig + install.sh).
- DMS settings: purple theme, popup transparency 0.98.

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

fontconfig/60-monospace-jetbrains.conf

@@ -0,0 +1,11 @@
+<?xml version="1.0"?>
+<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
+<fontconfig>
+  <!-- JetBrains Mono is the default monospace font for every program (instead of Noto Sans Mono / DejaVu) -->
+  <alias binding="same">
+    <family>monospace</family>
+    <prefer>
+      <family>JetBrains Mono</family>
+    </prefer>
+  </alias>
+</fontconfig>