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>

modules/home/ghostty.nix

@@ -8,11 +8,16 @@ let
   c = t.colors;
 in
 {
-  programs.ghostty = lib.mkIf config.nomarchy.ghostty.enable {
+  # Ghostty is ALWAYS installed — it's Nomarchy's default terminal and is
+  # load-bearing (SUPER+E file manager, the calendar launcher's classed
+  # window, etc.), so the distro enforces it. `nomarchy.ghostty.enable` now
+  # gates only whether Nomarchy's theming/config is applied — a user can
+  # keep ghostty but drop our config, they just can't remove ghostty itself.
+  programs.ghostty = {
     enable = true;
     enableBashIntegration = true;
 
-    settings = {
+    settings = lib.mkIf config.nomarchy.ghostty.enable {
       # ── Typography (from theme-state.json) ────────────────────────
       font-family = t.fonts.mono;
       font-size = t.fonts.size;