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/brands/affiliatetheme.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="M159.7 237.4C108.4 308.3 43.1 348.2 14 326.6-15.2 304.9 2.8 230 54.2 159.1 105.5 88.2 170.8 48.3 199.9 69.9s11.1 96.6-40.2 167.5zm351.2-57.3c-73.8 123.4-191.9 187.7-264.5 143.6-25-15.2-41.3-41.2-49-73.8-33.6 64.8-92.8 113.8-164.1 133.2 49.8 59.3 124.1 96.9 207 96.9 150 0 271.6-123.1 271.6-274.9 .1-8.5-.3-16.8-1-25z"/></svg>