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/toolbox.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="M176 56l0 40 160 0 0-40c0-4.4-3.6-8-8-8L184 48c-4.4 0-8 3.6-8 8zM128 96l0-40c0-30.9 25.1-56 56-56L328 0c30.9 0 56 25.1 56 56l0 40 28.1 0c12.7 0 24.9 5.1 33.9 14.1l51.9 51.9c9 9 14.1 21.2 14.1 33.9l0 76.1-136 0 0-16c0-13.3-10.7-24-24-24s-24 10.7-24 24l0 16-144 0 0-16c0-13.3-10.7-24-24-24s-24 10.7-24 24l0 16-136 0 0-76.1c0-12.7 5.1-24.9 14.1-33.9l51.9-51.9c9-9 21.2-14.1 33.9-14.1L128 96zM0 416l0-96 136 0 0 16c0 13.3 10.7 24 24 24s24-10.7 24-24l0-16 144 0 0 16c0 13.3 10.7 24 24 24s24-10.7 24-24l0-16 136 0 0 96c0 35.3-28.7 64-64 64L64 480c-35.3 0-64-28.7-64-64z"/></svg>