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/time_trigger.cpp

@@ -0,0 +1,46 @@
+#include "time_trigger.hpp"
+#include <boost/date_time/posix_time/posix_time.hpp>
+#include <iostream>
+#include <functional>
+
+namespace asio = boost::asio;
+namespace posix_time = boost::posix_time;
+using namespace vanetza;
+
+TimeTrigger::TimeTrigger(asio::io_context& io_context) :
+    io_context_(io_context), timer_(io_context), runtime_(Clock::at(now()))
+{
+    std::cout << "Starting runtime at " << now() <<"\n";
+    schedule();
+}
+
+posix_time::ptime TimeTrigger::now() const
+{
+    return posix_time::microsec_clock::universal_time();
+}
+
+void TimeTrigger::schedule()
+{
+    update_runtime();
+    auto next = runtime_.next();
+    if (next < Clock::time_point::max()) {
+        auto timeout = next - runtime_.now();
+        timer_.expires_after(timeout);
+        timer_.async_wait(std::bind(&TimeTrigger::on_timeout, this, std::placeholders::_1));
+    } else {
+        timer_.cancel();
+    }
+}
+
+void TimeTrigger::on_timeout(const boost::system::error_code& ec)
+{
+    if (asio::error::operation_aborted != ec) {
+        schedule();
+    }
+}
+
+void TimeTrigger::update_runtime()
+{
+    auto current_time = now();
+    runtime_.trigger(Clock::at(current_time));
+}