sway/waybar: fix muted glyph, dedupe bar on reload, relocate clock, match lock wallpaper

- Switch muted glyph from U+F6A9 to U+F026 (volume-off), which is
  present in every Nerd Font variant including LiterationMono.
- Use exec for waybar instead of exec_always, so reloading sway no
  longer spawns a second bar.
- Move the clock to the right of the tray and drop the leading
  calendar glyph from its format.
- Lock screen now uses maxresdefault.jpg, matching the i3 lockscreen;
  the asset is copied into sway/wallpapers/ so the sway profile stays
  self-contained.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

dotfiles/desktop/.config/sway/scripts/lockscreen

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 exec swaylock \
-    --image "$HOME/.config/sway/wallpapers/wallpaper-161664.jpg" \
+    --image "$HOME/.config/sway/wallpapers/maxresdefault.jpg" \
     --scaling fill \
     --indicator-idle-visible \
     --ring-color 2f4058 \