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/geonet/units.hpp

@@ -0,0 +1,37 @@
+#ifndef UNITS_HPP_O254IL9W
+#define UNITS_HPP_O254IL9W
+
+#include <boost/units/make_scaled_unit.hpp>
+#include <boost/units/quantity.hpp>
+#include <boost/units/systems/angle/degrees.hpp>
+#include <boost/units/systems/si/length.hpp>
+#include <cstdint>
+
+namespace vanetza
+{
+namespace geonet
+{
+
+// distance given in meter
+typedef boost::units::quantity<boost::units::si::length, uint16_t> distance_u16t;
+
+// geographical angles with 1/10 micro degree resolution
+typedef boost::units::quantity<boost::units::make_scaled_unit<
+            boost::units::degree::plane_angle,
+            boost::units::scale<10, boost::units::static_rational<-7>>
+        >::type, int32_t> geo_angle_i32t;
+
+// angle with 1 degree resolution
+typedef boost::units::quantity<boost::units::degree::plane_angle, uint16_t> angle_u16t;
+
+// heading with 0.1 degree resolution
+typedef boost::units::quantity<boost::units::make_scaled_unit<
+            boost::units::degree::plane_angle,
+            boost::units::scale<10, boost::units::static_rational<-1>>
+        >::type, uint16_t> heading_u16t;
+
+} // namespace geonet
+} // namespace vanetza
+
+#endif /* UNITS_HPP_O254IL9W */
+