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/book-medical.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! 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="M96 512l320 0c17.7 0 32-14.3 32-32s-14.3-32-32-32l0-66.7c18.6-6.6 32-24.4 32-45.3l0-288c0-26.5-21.5-48-48-48L96 0C43 0 0 43 0 96L0 416c0 53 43 96 96 96zM64 416c0-17.7 14.3-32 32-32l256 0 0 64-256 0c-17.7 0-32-14.3-32-32zM192 120c0-8.8 7.2-16 16-16l32 0c8.8 0 16 7.2 16 16l0 40 40 0c8.8 0 16 7.2 16 16l0 32c0 8.8-7.2 16-16 16l-40 0 0 40c0 8.8-7.2 16-16 16l-32 0c-8.8 0-16-7.2-16-16l0-40-40 0c-8.8 0-16-7.2-16-16l0-32c0-8.8 7.2-16 16-16l40 0 0-40z"/></svg>