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/shuttle-van.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 576 512"><!--! 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="M64 64C28.7 64 0 92.7 0 128L0 336c0 35.3 28.7 64 64 64l.4 0c4 44.9 41.7 80 87.6 80s83.6-35.1 87.6-80l104.7 0c4 44.9 41.7 80 87.6 80 46.1 0 83.9-35.4 87.7-80.5 31.7-3.8 56.3-30.8 56.3-63.5l0-101.3c0-13.8-4.5-27.3-12.8-38.4l-80-106.7C471.1 73.5 452.1 64 432 64L64 64zM504 224l-120 0 0-96 48 0 72 96zM64 224l0-96 96 0 0 96-96 0zm160 0l0-96 96 0 0 96-96 0zM392 392a40 40 0 1 1 80 0 40 40 0 1 1 -80 0zM152 352a40 40 0 1 1 0 80 40 40 0 1 1 0-80z"/></svg>