Fix wallpaper persistence, tray icons, Booru bugs, session launcher

- Persist last-set wallpaper and restore it via exec-once, since
  hyprpaper/mpvpaper start every session with nothing loaded
- Fix Vesktop's system tray icon rendering as a broken texture: only
  resolve tray icons through the icon theme when they're actual names,
  not raw pixmap-sourced image:// URLs
- Launch Hyprland via start-hyprland (its official watchdog launcher)
  instead of the raw binary, removing the startup warning and adding
  hang recovery
- Fix Booru panel: Lewds toggle now actually persists, tag autocomplete
  no longer drops/races overlapping requests, and pagination wraps
  instead of overflowing off-screen
- Remove the redundant gap between windows and sidebars/tiles
  (gaps_in/gaps_out, and duplicate flyout margins stacked on top of
  Hyprland's automatic exclusive-zone inset)

hyprland/hyprland.conf

@@ -29,6 +29,10 @@ source = ~/.config/hypr/display.conf
 # TTY) since only one agent can be registered at a time.
 exec-once = mako
 exec-once = hyprpaper
+# Reapplies whatever wallpaper was last set — hyprpaper/mpvpaper start every
+# session with nothing loaded, and wallpaper-set never persisted anything
+# on its own (see modules/scripts/wallpaper-set.sh, wallpaper-restore.sh).
+exec-once = wallpaper-restore
 exec-once = quickshell
 
 # GTK/Qt apps native-Wayland where possible, X11 fallback otherwise