Ship out-of-the-box VSCode-style config and sharp rendering defaults

- quilt patch: first-run user init.lua template now writes a tuned
  default config (Dark Modern theme, JetBrains Mono with grayscale AA,
  line-height/indent guides, compact treeview with hover highlight)
- new theme module usr/share/lite-xl/colors/vscode_dark.lua
- default config in /etc/skel/.config/lite-xl/ for new users
- desktop: launch via SDL software renderer with LITE_SCALE=1.5 so text
  renders 1:1 on fractional-scaled Wayland outputs and avoids panfrost
  GPU artifacts
- depend on fonts-jetbrains-mono for the default code font

.gitignore

@@ -25,3 +25,6 @@ LiteXL*
 !resources/macos/*.py
 !scripts/innosetup/lite-xl@*.bmp
 !scripts/innosetup/lite-xl-banner@*.bmp
+debian/.debhelper/
+debian/files
+debhelper-build-stamp