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/pills.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="M64 112c0-26.5 21.5-48 48-48s48 21.5 48 48l0 112-96 0 0-112zM176 368c0-48.7 18.1-93.2 48-127l0-129C224 50.1 173.9 0 112 0S0 50.1 0 112L0 400c0 61.9 50.1 112 112 112 37.3 0 70.3-18.2 90.7-46.3-17-28.6-26.7-62-26.7-97.7zm64.7 67.4c4.6 8.7 16.3 9.7 23.3 2.7L438.1 264c7-7 6-18.7-2.7-23.3-20.1-10.7-43-16.7-67.4-16.7-79.5 0-144 64.5-144 144 0 24.3 6 47.3 16.7 67.4zM297.9 472c-7 7-6 18.7 2.7 23.3 20.1 10.7 43 16.7 67.4 16.7 79.5 0 144-64.5 144-144 0-24.3-6-47.3-16.7-67.4-4.6-8.7-16.3-9.7-23.3-2.7L297.9 472z"/></svg>