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/hand.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="M288 32c0-17.7-14.3-32-32-32s-32 14.3-32 32l0 208c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-176c0-17.7-14.3-32-32-32s-32 14.3-32 32l0 272c0 1.5 0 3.1 .1 4.6L67.6 283c-16-15.2-41.3-14.6-56.6 1.4S-3.6 325.7 12.4 341L124.8 448c43.1 41.1 100.4 64 160 64l19.2 0c97.2 0 176-78.8 176-176l0-208c0-17.7-14.3-32-32-32s-32 14.3-32 32l0 112c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-176c0-17.7-14.3-32-32-32s-32 14.3-32 32l0 176c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-208z"/></svg>