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/plane-circle-check.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! 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="M232 24c0-30.9 25.1-56 56-56s56 25.1 56 56l0 127.3 78 71.5c-69.3 29-118 97.4-118 177.2 0 49.3 18.6 94.3 49.1 128.3L288 512 179.9 539c-10.1 2.5-19.9-5.1-19.9-15.5l0-19.8c0-4.9 2.2-9.5 6-12.5l66-52.8 0-99.7-162.9 54.3C58.7 396.4 48 388.7 48 377.8l0-43.7c0-9 3.8-17.5 10.4-23.6L232 151.3 232 24zM352 400a144 144 0 1 1 288 0 144 144 0 1 1 -288 0zm201.4-60.9c-7.1-5.2-17.2-3.6-22.4 3.5l-53 72.9-26.8-26.8c-6.2-6.2-16.4-6.2-22.6 0s-6.2 16.4 0 22.6l40 40c3.3 3.3 7.9 5 12.6 4.6s8.9-2.8 11.7-6.5l64-88c5.2-7.1 3.6-17.2-3.5-22.3z"/></svg>