(#1) - WebPack bundling of JS and CSS (#1)

This work was done with Claude.

Added bundling of CSS & JS with WebPack. This also means minimization.

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Co-authored-by: Martin Slachta <martin.slachta@outlook.com>
Reviewed-on: #1

assets/js/elements/RsvCalendar.js

@@ -1,4 +1,4 @@
-const RsvCalendarPicker = (() => {
+export const RsvCalendarPicker = (() => {
 
   function get_first_day_of_month(date) {
     const day = new Date(date.getFullYear(), date.getMonth(), 1).getDay();