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>

themes/boreal/waybar.css

@@ -23,7 +23,11 @@
 @define-color warn      #E6C384;
 @define-color bad       #E2818A;
 
-* {
+/* Scoped to the bar window: Waybar's stylesheet applies process-wide, so a
+   bare `*` also hits the SNI tray menus Waybar hosts (nm-applet & co) —
+   `min-height: 0` there collapses the submenu arrow node to invisible. */
+window#waybar,
+window#waybar * {
   /* Mono Nerd face for status glyphs (tight right bearings on the
      proportional Symbols face make icon+percentage collide). */
   font-family: "GeistMono Nerd Font", "Symbols Nerd Font Mono";
@@ -165,5 +169,10 @@ tooltip {
   background: alpha(@base, 0.96);
   border: 1px solid alpha(@accentAlt, 0.3);
   border-radius: 10px;
+  /* Tooltips are separate toplevels, outside the window#waybar scope —
+     restate the bar font (calendar/calcurse columns need the mono face). */
+  font-family: "GeistMono Nerd Font", "Symbols Nerd Font Mono";
+  font-size: 13px;
+  font-weight: 500;
 }
 tooltip label { color: @text; }