fix(waybar): drop the bar to the bottom layer so fullscreen covers it

On Hyprland the `top` layer renders above every window, including a real
fullscreen surface — so a browser video gone fullscreen sat *under* the
bar (BACKLOG item 30). Move the bar to `layer: bottom` in the generated
waybar.nix and all four whole-swap jsoncs (parity rule); the exclusive
zone still reserves its space in normal tiling, but a fullscreen window
now covers it. Rationale comment kept in waybar.nix; data jsoncs left
comment-free (they carry none).

Verified: V0 (nix flake check --no-build, green) + V1
(homeConfigurations.nomarchy.activationPackage builds; built
.config/waybar/config shows "layer": "bottom"). V3 queued in
HARDWARE-QUEUE (fullscreen covers bar + returns on exit; floating-overlap
trade-off).

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

agent/HARDWARE-QUEUE.md

@@ -222,6 +222,14 @@ QA machine), the **T14s** (webcam case).
       draining. (Crossing logic VM-verified — this checks the real
       swaync rendering in a session.)
 
+- [ ] **Waybar hides under fullscreen video** (item 30) — after
+      `home-update` + relogin, put a browser video (YouTube) into
+      fullscreen (F): the bar is now *covered* by the video, not drawn
+      on top; exit fullscreen → the bar returns. Normal tiling
+      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.
+
 ## AMD dev box only
 - [ ] **AMD runtime bits** — VA-API (`vainfo` → radeonsi), amd-pstate EPP
       active and PPD switching governors; opt-ins: ROCm (`rocminfo`, a GPU