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/certify-pqc/certificate_builder.hpp

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <vanetza/common/clock.hpp>
+#include <vanetza/common/its_aid.hpp>
+#include <vanetza/security/ecdsa256.hpp>
+#include <vanetza/security/pqc/fndsa512.hpp>
+#include <vanetza/security/v3/certificate.hpp>
+#include <string>
+#include <vector>
+
+namespace vanetza
+{
+namespace security
+{
+
+class Backend;
+
+namespace pqc
+{
+namespace certificate_builder
+{
+
+struct CertificateParameters
+{
+    std::string subject_name;
+    int validity_days = 1;
+    std::vector<ItsAid> application_ids;
+};
+
+v3::Certificate build_ecc_root_certificate(
+    ::vanetza::security::Backend&, const ecdsa256::KeyPair&,
+    const CertificateParameters&, Clock::time_point now);
+
+v3::Certificate build_hybrid_root_certificate(
+    ::vanetza::security::Backend&, Backend&, const ecdsa256::KeyPair&, const KeyPair&,
+    const CertificateParameters&, Clock::time_point now);
+
+v3::Certificate build_ecc_authorization_authority_certificate(
+    ::vanetza::security::Backend&, const ecdsa256::KeyPair& issuer_key,
+    const v3::Certificate& issuer_certificate,
+    const ecdsa256::PublicKey& subject_key,
+    const CertificateParameters&, Clock::time_point now);
+
+v3::Certificate build_hybrid_authorization_authority_certificate(
+    ::vanetza::security::Backend&, Backend&,
+    const ecdsa256::KeyPair& issuer_key, const PrivateKey& issuer_pqc_key,
+    const v3::Certificate& issuer_certificate,
+    const ecdsa256::PublicKey& subject_key, const PublicKey& subject_pqc_key,
+    const CertificateParameters&, Clock::time_point now);
+
+v3::Certificate build_ecc_authorization_ticket(
+    ::vanetza::security::Backend&, const ecdsa256::KeyPair& issuer_key,
+    const v3::Certificate& issuer_certificate,
+    const ecdsa256::PublicKey& subject_key,
+    const CertificateParameters&, Clock::time_point now);
+
+v3::Certificate build_hybrid_authorization_ticket(
+    ::vanetza::security::Backend&, Backend&,
+    const ecdsa256::KeyPair& issuer_key, const PrivateKey& issuer_pqc_key,
+    const v3::Certificate& issuer_certificate,
+    const ecdsa256::PublicKey& subject_key,
+    const CertificateParameters&, Clock::time_point now);
+
+} // namespace certificate_builder
+} // namespace pqc
+} // namespace security
+} // namespace vanetza