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/asn1/vam.hpp

@@ -0,0 +1,29 @@
+#ifndef VAM_HPP_RSEIP89V
+#define VAM_HPP_RSEIP89V
+
+#include <vanetza/asn1/asn1c_conversion.hpp>
+#include <vanetza/asn1/asn1c_wrapper.hpp>
+#include <vanetza/asn1/its/r2/VAM.h>
+
+namespace vanetza
+{
+namespace asn1
+{
+
+
+namespace r2
+{
+
+class Vam : public asn1c_per_wrapper<Vanetza_ITS2_VAM_t>
+{
+public:
+    Vam() : asn1c_per_wrapper(asn_DEF_Vanetza_ITS2_VAM) {}
+};
+
+} // namespace r2
+
+
+} // namespace asn1
+} // namespace vanetza
+
+#endif /* VAM_HPP_RSEIP89V */