Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/vanetza/gnss/wgs84point.hpp

@@ -0,0 +1,20 @@
+#ifndef WGS84POINT_HPP_GAHDJKCG
+#define WGS84POINT_HPP_GAHDJKCG
+
+#include <vanetza/units/angle.hpp>
+
+namespace vanetza
+{
+
+struct Wgs84Point
+{
+    typedef units::GeoAngle angle_type;
+    Wgs84Point(angle_type latitude, angle_type longitude) : lat(latitude), lon(longitude) {}
+    angle_type lat;
+    angle_type lon;
+};
+
+} // namespace vanetza 
+
+#endif /* WGS84POINT_HPP_GAHDJKCG */
+