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/ruler-combined.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="M1 441.7C5.5 463.5 24.8 480 48 480l352 0c26.5 0 48-21.5 48-48l0-96c0-26.5-21.5-48-48-48l-48 0 0 72c0 13.3-10.7 24-24 24s-24-10.7-24-24l0-72-64 0 0 72c0 13.3-10.7 24-24 24s-24-10.7-24-24l0-72-72 0c-13.3 0-24-10.7-24-24s10.7-24 24-24l72 0 0-64-72 0c-13.3 0-24-10.7-24-24s10.7-24 24-24l72 0 0-48c0-26.5-21.5-48-48-48L48 32C21.5 32 0 53.5 0 80L0 432c0 3.3 .3 6.6 1 9.7z"/></svg>