40C3: tours, schedule data, tour map and calendar entries

- tour-map shortcode: Leaflet map of the tour locations with routes from the
  Congress, from the map/tours sections of data/schedule/<event>.yaml; Leaflet
  and the OSMIC, Maki and Temaki icon sets vendored; 39C3 uMap data converted.
- calendar shortcode: per tour date, a pill with an .ics download (iCalendar)
  and a Google Calendar link; Font Awesome Free vendored, fa-icon partial.
- README sections for the calendar and tour map shortcodes and the map data.

assets/vendor/fontawesome/brands/hotjar.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 7.3.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2026 Fonticons, Inc. --><path fill="currentColor" d="M361.8 0c0 131.6-80.7 176.8-140.2 209.4-.6 .3-1.1 .6-1.6 .9-53.8 30.2-88.7 49.8-89.6 122l-98.1 0c0-131.5 80.7-176.7 140.2-209.3 54.8-29.8 90.3-50 90.3-123l99 0zM301.3 302.6c54.8-29.8 90.3-50 90.3-123l98 0c0 131.6-80.7 176.7-140.2 209.4-54.8 29.8-90.3 50-90.3 123l-98 0c0-131.6 80.7-176.8 140.2-209.4z"/></svg>