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/waybar/config.jsonc

@@ -5,8 +5,8 @@
   "spacing": 4,
 
   "modules-left":   ["sway/workspaces"],
-  "modules-center": ["clock"],
-  "modules-right":  ["cpu", "memory", "disk", "temperature", "backlight", "network", "pulseaudio", "battery", "tray"],
+  "modules-center": [],
+  "modules-right":  ["cpu", "memory", "disk", "temperature", "backlight", "network", "pulseaudio", "battery", "tray", "clock"],
 
   "sway/workspaces": {
     "disable-scroll": true,
@@ -31,7 +31,7 @@
 
   "clock": {
     "interval": 60,
-    "format": " {:%Y-%m-%d %H:%M}",
+    "format": "{:%Y-%m-%d %H:%M}",
     "tooltip-format": "<tt>{calendar}</tt>"
   },
 
@@ -74,7 +74,7 @@
 
   "pulseaudio": {
     "format":           "{icon} {volume}%",
-    "format-muted":     " muted",
+    "format-muted":     " muted",
     "format-bluetooth": "{icon} {volume}% ",
     "format-icons":     { "default": ["", "", ""] },
     "on-click":         "swayosd-client --output-volume mute-toggle",