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/puzzle-piece.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! 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="M224 0c35.3 0 64 21.5 64 48 0 10.4-4.4 20-12 27.9-6.6 6.9-12 15.3-12 24.9 0 15 12.2 27.2 27.2 27.2l44.8 0c26.5 0 48 21.5 48 48l0 44.8c0 15 12.2 27.2 27.2 27.2 9.5 0 18-5.4 24.9-12 7.9-7.5 17.5-12 27.9-12 26.5 0 48 28.7 48 64s-21.5 64-48 64c-10.4 0-20.1-4.4-27.9-12-6.9-6.6-15.3-12-24.9-12-15 0-27.2 12.2-27.2 27.2L384 464c0 26.5-21.5 48-48 48l-56.8 0c-12.8 0-23.2-10.4-23.2-23.2 0-9.2 5.8-17.3 13.2-22.8 11.6-8.7 18.8-20.7 18.8-34 0-26.5-28.7-48-64-48s-64 21.5-64 48c0 13.3 7.2 25.3 18.8 34 7.4 5.5 13.2 13.5 13.2 22.8 0 12.8-10.4 23.2-23.2 23.2L48 512c-26.5 0-48-21.5-48-48L0 343.2c0-12.8 10.4-23.2 23.2-23.2 9.2 0 17.3 5.8 22.8 13.2 8.7 11.6 20.7 18.8 34 18.8 26.5 0 48-28.7 48-64s-21.5-64-48-64c-13.3 0-25.3 7.2-34 18.8-5.5 7.4-13.5 13.2-22.8 13.2-12.8 0-23.2-10.4-23.2-23.2L0 176c0-26.5 21.5-48 48-48l108.8 0c15 0 27.2-12.2 27.2-27.2 0-9.5-5.4-18-12-24.9-7.5-7.9-12-17.5-12-27.9 0-26.5 28.7-48 64-48z"/></svg>