feat(waybar): open a calendar (calcurse) on the clock click

Item 42, de-scoped by Bernardo to app-only — no account sync (the user
configures that themselves locally). Clicking the Waybar date/clock now
runs nomarchy-calendar → calcurse in a floating, centered ghostty window
tagged --class=com.nomarchy.calendar (+ --gtk-single-instance=false for a
fresh standalone window), matched by a float+size+center windowrule. The
launcher self-gates on calcurse. Dropped the clock's format-alt date
toggle (conflicts with on-click) and moved the long date into the tooltip.
Parity: on-click added to all four whole-swap jsoncs.

Ships calcurse + pwvucontrol uncommented in the downstream template
(opt-out). Enforces ghostty always installed (ghostty.nix: enable = true
unconditional; nomarchy.ghostty.enable now gates only the theming/config)
so the --class launcher can rely on it.

Verified: V0 green; four jsoncs valid JSON; V1 HM built — launcher ships,
generated clock renders on-click=nomarchy-calendar (format-alt gone, date
in tooltip), hyprland has the 3 calendar windowrules, ghostty in the HM
profile. Click→float→calcurse month view is V3 (queued). Sync is
deliberately the user's own config, not a distro feature.

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

agent/HARDWARE-QUEUE.md

@@ -293,6 +293,17 @@ QA machine), the **T14s** (webcam case).
       night, executive-slate, boreal) behave the same and their shutdown
       power-button (if present) still opens the lock/logout menu.
 
+- [ ] **Calendar on the clock click** (iteration #68, item 42) — after
+      `home-update` + relogin: left-click the Waybar date/clock → calcurse
+      opens in a **floating, centered** ghostty window (~60×65% of screen),
+      showing the month calendar; closing calcurse (`q`) closes the window.
+      The `--class=com.nomarchy.calendar` must match the windowrule (if it
+      tiles, run `hyprctl clients` while open and check the real app-id).
+      Hover the clock → tooltip shows the long date + zone + month grid.
+      Same on a whole-swap bar (summer/boreal/executive-slate). If calcurse
+      was removed from home.packages, the click toasts "calcurse isn't
+      installed" instead of doing nothing.
+
 ## 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