fix(waybar): scope the universal CSS reset to the bar — un-hides tray submenu arrows

BACKLOG #90 root-caused: the arrows were never missing from the icon
theme — Papirus-Dark resolves pan-end-symbolic through its breeze-dark
inheritance (breeze ships inside the nixpkgs papirus output). The real
culprit: Waybar loads its stylesheet screen-wide at application
priority, so the tray menus it hosts for SNI apps (nm-applet & co)
inherit the bar's '* { min-height: 0; }', which out-prioritizes
adw-gtk3's 16px min-height on the menuitem arrow node and collapses
the submenu arrow to zero height. Property bisect confirmed
min-height:0 alone reproduces; the font/border resets don't.

- boreal + executive-slate waybar.css, waybar.nix generatedStyle:
  '*' block scoped to 'window#waybar, window#waybar *'; tooltip rules
  restate the font (tooltips are separate toplevels outside the scope).
- stylix.nix: drop the go-next-symbolic remap — a workaround for the
  misdiagnosis; native pan-end-symbolic resolves fine.
- BACKLOG #90 deleted; JOURNAL entry records the method (live GTK3
  repro + grim screenshots + CSS property bisect, V3 on TuringMachine).

V3 pending: human click on the real nm-applet tray icon post-switch.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent/JOURNAL.md

@@ -19,6 +19,24 @@ Template:
 
 ---
 
+## 2026-07-12 — #90 tray submenu arrows: root cause was waybar CSS (this commit)
+- **Task:** BACKLOG #90 `[stuck]` (interactive, Bernardo driving on T14s).
+- **Did:** Diagnosis was wrong — Papirus-Dark resolves `pan-end-symbolic`
+  fine via its breeze-dark inheritance (breeze ships inside the nixpkgs
+  papirus output). Real cause: Waybar's stylesheet applies process-wide,
+  and the `* { min-height: 0; }` block collapsed the arrow node in the
+  SNI tray menus Waybar hosts. Scoped the `*` block to `window#waybar`
+  in boreal + executive-slate waybar.css and waybar.nix generatedStyle
+  (tooltip rules restate the font — tooltips are separate toplevels);
+  removed the go-next-symbolic remap workaround from stylix.nix.
+- **Verified:** **V3** — live GTK3 repro app popping a dbusmenu-shaped
+  menu, screenshotted via grim: arrow vanishes with old CSS injected
+  screen-wide, renders with fixed CSS; property bisect pinned
+  `min-height: 0` as the sole culprit. V1 flake check green.
+- **Pending:** post-switch check that the real nm-applet menu shows the
+  arrow (needs a human click on the tray icon).
+- **Next suggestion:** #89 slice 2 — the override-icon layer.
+
 ## 2026-07-11 — interactive T14s session: migration follow-ups (50a5586…6967d89)
 - **Task:** Escalation — Bernardo driving, live on the migrated T14s
   (first full session on real Nomarchy hardware; 7 commits).