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/traffic_class.hpp

@@ -0,0 +1,46 @@
+#ifndef TRAFFIC_CLASS_HPP_I2WYKREX
+#define TRAFFIC_CLASS_HPP_I2WYKREX
+
+#include <vanetza/common/bit_number.hpp>
+#include <vanetza/dcc/profile.hpp>
+#include <vanetza/geonet/serialization.hpp>
+#include <cstdint>
+
+namespace vanetza
+{
+
+namespace geonet
+{
+
+class TrafficClass
+{
+public:
+    TrafficClass();
+    TrafficClass(bool scf, bool channel_offload, BitNumber<unsigned, 6> tc_id);
+    explicit TrafficClass(uint8_t raw);
+
+    bool store_carry_forward() const;
+    void store_carry_forward(bool flag);
+    bool channel_offload() const;
+    void channel_offload(bool flag);
+    BitNumber<unsigned, 6> tc_id() const;
+    void tc_id(BitNumber<unsigned, 6> id);
+    uint8_t raw() const { return m_tc; }
+
+private:
+    static constexpr uint8_t scf_mask = 0x80;
+    static constexpr uint8_t channel_offload_mask = 0x40;
+    static constexpr uint8_t tc_id_mask = 0x3f;
+    uint8_t m_tc;
+};
+
+dcc::Profile map_tc_onto_profile(const TrafficClass&);
+
+void serialize(const TrafficClass&, OutputArchive&);
+void deserialize(TrafficClass&, InputArchive&);
+
+} // namespace geonet
+} // namespace vanetza
+
+#endif /* TRAFFIC_CLASS_HPP_I2WYKREX */
+