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/tools/socktap/benchmark_application.hpp

@@ -0,0 +1,27 @@
+#ifndef BENCHMARK_APPLICATION_HPP_EUIC2VFR
+#define BENCHMARK_APPLICATION_HPP_EUIC2VFR
+
+#include "application.hpp"
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/steady_timer.hpp>
+#include <chrono>
+
+class BenchmarkApplication : public Application, private Application::PromiscuousHook
+{
+public:
+    BenchmarkApplication(boost::asio::io_context&);
+    PortType port() override;
+    void indicate(const DataIndication&, UpPacketPtr) override;
+    Application::PromiscuousHook* promiscuous_hook() override;
+
+private:
+    void schedule_timer();
+    void on_timer(const boost::system::error_code& ec);
+    void tap_packet(const DataIndication&, const vanetza::UpPacket&) override;
+
+    boost::asio::steady_timer m_timer;
+    std::chrono::milliseconds m_interval;
+    unsigned m_received_messages;
+};
+
+#endif /* BENCHMARK_APPLICATION_HPP_EUIC2VFR */