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/brain.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="M120 56c0-30.9 25.1-56 56-56l24 0c17.7 0 32 14.3 32 32l0 448c0 17.7-14.3 32-32 32l-32 0c-29.8 0-54.9-20.4-62-48-.7 0-1.3 0-2 0-44.2 0-80-35.8-80-80 0-18 6-34.6 16-48-19.4-14.6-32-37.8-32-64 0-30.9 17.6-57.8 43.2-71.1-7.1-12-11.2-26-11.2-40.9 0-44.2 35.8-80 80-80l0-24zm272 0l0 24c44.2 0 80 35.8 80 80 0 15-4.1 29-11.2 40.9 25.7 13.3 43.2 40.1 43.2 71.1 0 26.2-12.6 49.4-32 64 10 13.4 16 30 16 48 0 44.2-35.8 80-80 80-.7 0-1.3 0-2 0-7.1 27.6-32.2 48-62 48l-32 0c-17.7 0-32-14.3-32-32l0-448c0-17.7 14.3-32 32-32l24 0c30.9 0 56 25.1 56 56z"/></svg>