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/periscope.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! 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="M370 63.6c-38.6-41-89.5-63.6-143.4-63.6-114.7 0-208.1 96.2-208.1 214.4 0 75.1 57.8 159.8 82.7 192.7 36.6 48.4 91.4 104.9 125.4 104.9 41.6 0 112.9-94.2 120.9-105 24.6-33.1 82-118.3 82-192.6 0-56.5-21.1-110.1-59.5-150.8zM226.6 493.9c-42.5 0-190-167.3-190-279.4 0-107.4 83.9-196.3 190-196.3 100.8 0 184.7 89 184.7 196.3 .1 112.1-147.4 279.4-184.7 279.4zM338 206.8c0 59.1-51.1 109.7-110.8 109.7-100.6 0-150.7-108.2-92.9-181.8l0 .4c0 24.5 20.1 44.4 44.8 44.4s44.8-19.9 44.8-44.4c0-18.2-11.1-33.8-26.9-40.7 76.6-19.2 141 39.3 141 112.4z"/></svg>