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/vest.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="M200 464l0-170.1c0-3.9-.5-7.8-1.4-11.6L144.4 65.4C162.1 77.2 188.2 88 224 88s61.9-10.8 79.6-22.6L249.4 282.3c-1 3.8-1.4 7.7-1.4 11.6L248 464c0 26.5 21.5 48 48 48l104 0c26.5 0 48-21.5 48-48l0-193.5c0-9.5-2.8-18.7-8.1-26.6l-47.9-71.8c-5.3-7.9-8.1-17.1-8.1-26.6L384 48c0-26.5-21.5-48-48-48l-3.5 0c-.3 0-.6 0-1 0-.6 0-1.2 0-1.8 0-18.8 0-34.1 9.7-44.1 18.8-9.3 8.4-28.5 21.2-61.7 21.2s-52.4-12.8-61.7-21.2c-10-9.1-25.3-18.8-44.1-18.8-.6 0-1.2 0-1.8 0-.3 0-.6 0-1 0L112 0C85.5 0 64 21.5 64 48l0 97.5c0 9.5-2.8 18.7-8.1 26.6L8.1 243.9C2.8 251.8 0 261.1 0 270.5L0 464c0 26.5 21.5 48 48 48l104 0c26.5 0 48-21.5 48-48z"/></svg>