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/solid/cab.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="M192 0c-17.7 0-32 14.3-32 32l0 32-8.9 0c-42 0-79.1 27.3-91.6 67.4l-23 73.5C14.5 219.1 0 243.9 0 272L0 448c0 17.7 14.3 32 32 32l32 0c17.7 0 32-14.3 32-32l0-32 320 0 0 32c0 17.7 14.3 32 32 32l32 0c17.7 0 32-14.3 32-32l0-176c0-28.1-14.5-52.9-36.4-67.1l-23-73.5C440.1 91.3 402.9 64 360.9 64l-8.9 0 0-32c0-17.7-14.3-32-32-32L192 0zM151.1 128l209.9 0c14 0 26.4 9.1 30.5 22.5l13 41.5-296.9 0 13-41.5c4.2-13.4 16.5-22.5 30.5-22.5zM96 272a32 32 0 1 1 0 64 32 32 0 1 1 0-64zm288 32a32 32 0 1 1 64 0 32 32 0 1 1 -64 0z"/></svg>