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>

agent/HARDWARE-QUEUE.md

@@ -236,6 +236,11 @@ QA machine), the **T14s** (webcam case).
       unchanged (the bar still reserves its space). Accepted trade-off
       of `layer: bottom`: a floating window dragged over the top strip
       can now overlap the bar — confirm that's the only regression.
+- [ ] **Right-click volume → floating mixer** (iteration #62, item 35) —
+      after `home-update` + relogin: right-click the Waybar volume module
+      opens pwvucontrol as a floating, centered window (not tiled);
+      left-click still mutes. Verify across a whole-swap theme too
+      (summer/boreal/executive-slate) since the jsoncs got the same wiring.
 - [ ] **Window focus on arrows** (iteration #61) — after `home-update` +
       relogin: SUPER+←/→/↑/↓ move focus between tiled windows; SUPER+H/J/K/L
       no longer move focus; SUPER+? cheatsheet shows the arrow glyphs.