feat(waybar): right-click volume opens a floating pwvucontrol mixer

Right-clicking the Waybar volume module now opens pwvucontrol (per-app
mixer); left-click still mutes. Adds:

- on-click-right in waybar.nix + all four whole-swap jsoncs (parity)
- hyprland.nix: the config's first windowrule block — float + center the
  mixer (pwvucontrol, with pavucontrol as a fallback class); normal-
  priority list so a downstream windowrule concatenates
- pwvucontrol in the template home.packages

pwvucontrol is PipeWire-native + GTK4/libadwaita, so it themes via the
portal color-scheme like Amberol. app-id verified from the built package.
This settles the windowrule pattern/placement; item 41 is now just
broadening the float set. Right-click→float→center is a V3 session check.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/home/hyprland.nix

@@ -438,6 +438,18 @@ in
         background_color = rgb c.base;
       };
 
+      # Window rules. This is the config's first float rule; item 41 will
+      # broaden the set (dialogs, portals, …) once that audit lands. For
+      # now: the audio mixer opened by right-clicking the Waybar volume
+      # module (item 35) floats + centers instead of tiling. Matches
+      # pwvucontrol (the template's mixer) and pavucontrol if swapped in.
+      # Normal-priority list like `bind`/`exec-once` below, so a downstream
+      # `windowrule = [...]` concatenates rather than replaces.
+      windowrule = [
+        "float, class:^(com\\.saivert\\.pwvucontrol|org\\.pulseaudio\\.pavucontrol|pavucontrol)$"
+        "center, class:^(com\\.saivert\\.pwvucontrol|org\\.pulseaudio\\.pavucontrol|pavucontrol)$"
+      ];
+
       # Rendered from ./keybinds.nix (the cheatsheet reads the same list),
       # plus the generated per-workspace binds. Like exec-once above this
       # stays a normal-priority list, so a downstream `bind = [...]`

modules/home/waybar.nix

@@ -172,6 +172,10 @@ let
       format-muted = "󰝟";
       format-icons.default = [ "󰕿" "󰖀" "󰕾" ];
       on-click = "wpctl set-mute @DEFAULT_AUDIO_SINK@ toggle";
+      # Right-click → the full mixer (per-app volumes) in a floating window
+      # (item 35). pwvucontrol ships in the template suite; the Hyprland
+      # windowrule floats it. Keep in sync with the whole-swap jsoncs.
+      on-click-right = "pwvucontrol";
     };
 
     # Idle inhibitor (caffeine): click 󰾪 → 󰅶 to hold the screen awake —