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/certificate_validation_v3.hpp

@@ -0,0 +1,64 @@
+#pragma once
+
+#include <vanetza/security/private_key.hpp>
+#include <memory>
+#include <string>
+
+namespace boost
+{
+namespace program_options
+{
+class options_description;
+class variables_map;
+} // namespace program_options
+} // namespace boost
+
+namespace vanetza
+{
+
+class PositionProvider;
+class Runtime;
+
+namespace security
+{
+
+class Backend;
+
+namespace v3
+{
+class Certificate;
+class CertificateValidator;
+class LocationChecker;
+} // namespace v3
+} // namespace security
+} // namespace vanetza
+
+/**
+ * Owns the profile-specific services selected for a socktap V3 security context.
+ *
+ * Profile-specific implementations may retain issuer certificates and trust
+ * anchors needed by their validator and select the credential format expected
+ * by that profile. The strict implementation preserves socktap's established
+ * behavior.
+ */
+class CertificateValidationV3
+{
+public:
+    virtual ~CertificateValidationV3() = default;
+
+    virtual vanetza::security::v3::CertificateValidator& validator() = 0;
+    virtual vanetza::security::PrivateKey load_authorization_ticket_key(
+        const std::string&) const = 0;
+    virtual void add_chain_certificate(const vanetza::security::v3::Certificate&) = 0;
+};
+
+std::unique_ptr<CertificateValidationV3> create_default_certificate_validation_v3(
+    const vanetza::Runtime&, vanetza::PositionProvider&,
+    const vanetza::security::v3::LocationChecker&);
+
+std::unique_ptr<CertificateValidationV3> create_certificate_validation_v3(
+    const boost::program_options::variables_map&, const vanetza::Runtime&,
+    vanetza::PositionProvider&, const vanetza::security::v3::LocationChecker&,
+    vanetza::security::Backend&);
+
+void add_certificate_validation_v3_options(boost::program_options::options_description&);