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/trash-restore.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="M167.1-16l113.9 0c13.8 0 26 8.8 30.4 21.9L320 32 416 32c17.7 0 32 14.3 32 32s-14.3 32-32 32L32 96C14.3 96 0 81.7 0 64S14.3 32 32 32l96 0 8.7-26.1C141.1-7.2 153.3-16 167.1-16zM32 144l384 0-21.1 323.1C393.3 492.4 372.3 512 347 512L101 512c-25.3 0-46.3-19.6-47.9-44.9L32 144zm209 79c-9.4-9.4-24.6-9.4-33.9 0l-72 72c-9.4 9.4-9.4 24.6 0 33.9s24.6 9.4 33.9 0l31-31 0 102.1c0 13.3 10.7 24 24 24s24-10.7 24-24l0-102.1 31 31c9.4 9.4 24.6 9.4 33.9 0s9.4-24.6 0-33.9l-72-72z"/></svg>