Add a calendar popup to the clock

Clicking the clock reveals a month grid with ISO week numbers, a year
progress meter, and month stepping. Right click walks the common label
formats and writes the chosen one back to shell.json, so the bar shows
what the config stores. The week start toggles from the grid's "W"
heading and persists as weekStartDay, defaulting to the locale's own
first day.

Rich popup widgets live in their own plugin directories, so the clock
moves out of bar/widgets/ into panels/clock/. The id is unchanged, so
existing layouts and centerAnchor keep working.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

default/hypr/bindings/utilities.lua

@@ -77,6 +77,7 @@ o.bind("SUPER + CTRL + ALT + W", "Toggle weather", "omarchy-notification-weather
 o.bind("SUPER + CTRL + A", "Audio", "omarchy-shell shell toggle omarchy.audio")
 o.bind("SUPER + CTRL + B", "Bluetooth", "omarchy-shell shell toggle omarchy.bluetooth")
 o.bind("SUPER + CTRL + D", "Display", "omarchy-shell shell toggle omarchy.monitor")
+o.bind("SUPER + CTRL + ALT + D", "Calendar", "omarchy-shell shell toggle omarchy.clock")
 o.bind("SUPER + CTRL + W", "Network", "omarchy-shell shell toggle omarchy.network")
 o.bind("SUPER + CTRL + P", "Power", "omarchy-shell shell toggle omarchy.power")
 o.bind("SUPER + CTRL + T", "Activity", { tui = "btop" })