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/person-circle-minus.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="M280 24a56 56 0 1 0 -112 0 56 56 0 1 0 112 0zm24 212.7L341 286.6c12.8-17.5 28.5-32.7 46.3-45l-56.2-75.7C306 132 266.3 112 224 112s-82 20-107.2 53.9l-70.5 95c-10.5 14.2-7.6 34.2 6.6 44.8s34.2 7.6 44.8-6.6L144 236.7 144 512c0 17.7 14.3 32 32 32s32-14.3 32-32l0-160c0-8.8 7.2-16 16-16s16 7.2 16 16l0 160c0 17.7 14.3 32 32 32s32-14.3 32-32l0-275.3zM640 400a144 144 0 1 0 -288 0 144 144 0 1 0 288 0zm-64 0c0 8.8-7.2 16-16 16l-128 0c-8.8 0-16-7.2-16-16s7.2-16 16-16l128 0c8.8 0 16 7.2 16 16z"/></svg>