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/house-lock.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512"><!--! 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="M528 224.1c44.2 0 80 35.8 80 80l0 50.6c18.6 6.6 32 24.4 32 45.3l0 96c0 26.5-21.5 48-48 48l-128 0c-26.5 0-48-21.5-48-48l0-96c0-20.9 13.4-38.7 32-45.3l0-50.6c0-44.2 35.8-80 80-80zM268.6 6.5c12.2-9.3 29.7-8.7 41.2 2l185 171.8C440.2 195 400 244.8 400 304l0 24.4c-19.6 17.6-32 43.1-32 71.5l0 96c0 5.5 .5 10.9 1.3 16.1L144 512c-35.3 0-64-28.7-64-64l0-176-16 0c-13.2 0-25-8.1-29.8-20.3s-1.6-26.2 8-35.1l224-208 2.4-2zM272 320c-26.5 0-48 21.5-48 48l0 96 96 0 0-87.3c0-16.5 7-31.5 18.4-42.1-8.7-9-20.9-14.6-34.4-14.6l-32 0zm256-47.9c-17.7 0-32 14.3-32 32l0 47.9 64 0 0-47.9c0-17.7-14.3-32-32-32z"/></svg>