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/paintbrush.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="M480.5 10.3L259.1 158c-29.1 19.4-47.6 50.9-50.6 85.3 62.3 12.8 111.4 61.9 124.3 124.3 34.5-3 65.9-21.5 85.3-50.6L565.7 95.5c6.7-10.1 10.3-21.9 10.3-34.1 0-33.9-27.5-61.4-61.4-61.4-12.1 0-24 3.6-34.1 10.3zM288 400c0-61.9-50.1-112-112-112S64 338.1 64 400c0 3.9 .2 7.8 .6 11.6 1.8 17.5-10.2 36.4-27.8 36.4L32 448c-17.7 0-32 14.3-32 32s14.3 32 32 32l144 0c61.9 0 112-50.1 112-112z"/></svg>