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/id-card-alt.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="M256-32l64 0c17.7 0 32 14.3 32 32l0 64-128 0 0-64c0-17.7 14.3-32 32-32zM64 32l112 0 0 32c0 26.5 21.5 48 48 48l128 0c26.5 0 48-21.5 48-48l0-32 112 0c35.3 0 64 28.7 64 64l0 320c0 35.3-28.7 64-64 64L64 480c-35.3 0-64-28.7-64-64L0 96C0 60.7 28.7 32 64 32zM176 400c0 8.8 7.2 16 16 16l192 0c8.8 0 16-7.2 16-16 0-44.2-35.8-80-80-80l-64 0c-44.2 0-80 35.8-80 80zM288 280a56 56 0 1 0 0-112 56 56 0 1 0 0 112z"/></svg>