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/square-deskpro.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! 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="M408.8 32C430.4 32 448 49.6 448 71.2l0 369.6c0 21.6-17.6 39.2-39.2 39.2L39.2 480C17.6 480 0 462.4 0 440.8L0 71.2C0 49.6 17.6 32 39.2 32l369.6 0zM110.9 274.1l0 114.4 89.1-.1c20.6 0 39.4-3.2 56.3-9.5s31.3-15.4 43.2-27c12.2-11.9 21.6-26 28.2-42.1 4.6-11.1 7.7-23 9.2-35.7l-43.8 0c-1.1 6.4-2.8 12.4-5.1 18.2-4.2 10.9-10.3 20.3-18.2 28.2-7.9 7.7-17.4 13.7-28.6 17.9-11.1 4.3-23.5 6.4-37.3 6.4l-50 0 0-70.6-43 .1zm0-151.4l0 114.4 43-.1 0-70.7 50 0c13.7 0 26.2 2.1 37.3 6.4 11.1 4.3 20.6 10.3 28.6 18.3 7.9 7.7 14 17.1 18.2 28.2 2.3 5.6 4 11.5 5.1 17.8l43.9 .1c-1.4-12.6-4.4-24.4-8.9-35.3-6.6-16.4-16-30.5-28.1-42.2-12.1-11.9-26.7-21.1-43.6-27.5-16.9-6.4-35.7-9.5-56.3-9.5l-89 .1z"/></svg>