fix(ui): #139 sheets size themselves; #141 waybar clicks stop reading the env

#139 — calcurse/doctor floated full-screen. Two faults stacked, which is
why it looked like the float rules were dead:
  1. Hyprland 0.55.4 silently ignores percentage `size` rules. Matrix on
     hardware (both orders, kitty memory off): `size 60% 65%` never
     applies, `size 1536 936` applies either way, configerrors empty both
     times. Rule order was a red herring.
  2. Kitty defaults to remember_window_size=yes and replays the last OS
     window's size into every float — so after a tiled terminal, a sheet
     opens maximized. This is the Ghostty regression: Ghostty had no such
     memory, so fault 1 stayed invisible until #95.

Fix: remember_window_size=no (floats must be deterministic) and the sheets
ask for their own size — term-sheet.nix reads the focused monitor and
hands kitty the px, because px in a rule cannot mean "a fraction of *this*
screen" and one pair cannot serve 2560x1440 and the 1366x768 Acer (#131).
Those windows keep float/center and deliberately carry no size rule.

#141 — the updates click did nothing: whole-swaps hand-wrote
`sh -c '$TERMINAL …'` and Waybar has no TERMINAL (home.sessionVariables →
login shells only; the bar is spawned by Hyprland). Fixed at the root:
`nomarchy-updates upgrade-window` opens its own window, so all five call
sites name one env-free command and a theme file stops having an opinion
about terminals. checks.waybar-swap-env guards the class.

Bernardo asked mid-task for the update window to float — it is now the
third caller of the sheet helper (com.nomarchy.updates, 45%x50%).

V3 on the dev box: calendar 1536x936, doctor 1408x1008, updates 1152x720
— exactly the intended fractions, floating and centred; #141 driven under
`env -i` with no TERMINAL, matching Waybar's real environment; the guard
proven by reintroducing the bug. Acer V3 queued.

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

themes/executive-slate/waybar.jsonc

@@ -79,7 +79,7 @@
     "interval": 1800,
     "signal": 9,
     "exec": "nomarchy-updates status",
-    "on-click": "sh -c '$TERMINAL -e nomarchy-updates upgrade'"
+    "on-click": "nomarchy-updates upgrade-window"
   },
   "pulseaudio": {
     "scroll-step": 5,