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/aquarius.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="M401.7 291.4c9-4.5 19.6-4.5 28.6 0l128 64c15.8 7.9 22.2 27.1 14.3 42.9s-27.1 22.2-42.9 14.3L416 355.8 302.3 412.6c-9 4.5-19.6 4.5-28.6 0L160 355.8 46.3 412.6c-15.8 7.9-35 1.5-42.9-14.3s-1.5-35 14.3-42.9l128-64c9-4.5 19.6-4.5 28.6 0L288 348.2 401.7 291.4zm3.4-193.5c8.2-3 17.3-2.5 25.2 1.5l128 64c15.8 7.9 22.2 27.1 14.3 42.9s-27.1 22.2-42.9 14.3L416 163.8 302.3 220.6c-9 4.5-19.6 4.5-28.6 0L160 163.8 46.3 220.6c-15.8 7.9-35 1.5-42.9-14.3s-1.5-35 14.3-42.9l128-64 3.4-1.5c8.2-3 17.3-2.5 25.2 1.5l113.7 56.8 113.7-56.8 3.4-1.5z"/></svg>