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/pki/prune_command.hpp

@@ -0,0 +1,110 @@
+#pragma once
+
+#include "certificate.hpp"
+#include "certificate_storage.hpp"
+#include "hashed_id8.hpp"
+#include "main.hpp"
+#include <vanetza/common/clock.hpp>
+#include <CLI/CLI.hpp>
+#include <memory>
+#include <string>
+
+namespace vanetza
+{
+namespace pki
+{
+
+/**
+ * Visitor that observes expired certificates streamed by `prune_expired`.
+ * Methods are called once per certificate as it is encountered. The driver
+ * performs no per-cert buffering.
+ */
+class PruneExpiredVisitor
+{
+public:
+    virtual ~PruneExpiredVisitor() = default;
+
+    /**
+     * An expired certificate eligible for deletion.
+     *
+     * \param store      backing store holding the cert; the visitor erases from it if needed
+     * \param label      short role tag ("Root CA", "EC", "AT", "TLM") for output
+     * \param pubkey_hex canonical-hex name of the corresponding credential
+     */
+    virtual void on_deletable(CertificateStorage& store, const std::string& label, const HashedId8&, const Certificate&,
+        const std::string& pubkey_hex)
+    {
+    }
+
+    /**
+     * An expired certificate that is being skipped because it is referenced
+     * by station configuration and `--force` was not specified.
+     */
+    virtual void on_skipped(const std::string& label, const HashedId8&, const Certificate&)
+    {
+    }
+
+    /// Called once after all stores have been fully iterated.
+    virtual void on_summary()
+    {
+    }
+};
+
+/**
+ * Stream every expired certificate in the cert and ticket stores through the
+ * visitor. Memory is constant — no per-cert state is retained.
+ *
+ * \param now   cutoff for expiry: `cert.valid_until() < now` ⇒ expired
+ * \param force if true, station-referenced certs go to `on_deletable` instead
+ *              of `on_skipped`
+ */
+void prune_expired(const MainConfig& cfg, Clock::time_point now, bool force, PruneExpiredVisitor& visitor);
+
+/**
+ * Prune expired authorization tickets and their credentials.
+ * `dry_run` lists without deleting.
+ */
+void prune_expired_tickets(const MainConfig& cfg, Clock::time_point now, bool dry_run);
+
+/// Visitor for `prune_orphans`. Same streaming pattern.
+class PruneOrphansVisitor
+{
+public:
+    virtual ~PruneOrphansVisitor() = default;
+
+    /// An orphan credential eligible for deletion, by canonical-hex name.
+    virtual void on_orphan(const std::string& canonical_hex)
+    {
+    }
+
+    /// A credential retained because a certificate still references it.
+    virtual void on_keep(const std::string& canonical_hex)
+    {
+    }
+
+    /// Called once after all credentials have been iterated.
+    virtual void on_summary()
+    {
+    }
+};
+
+/**
+ * Stream every orphan credential through the visitor.
+ * A credential is orphan when its canonical-hex name does not match any public key
+ * referenced by a certificate in either store.
+ */
+void prune_orphans(const MainConfig& cfg, PruneOrphansVisitor& visitor);
+
+/**
+ * Reconcile the exported AA/EA issuer certificates against the currently stored
+ * CTLs: remove any `.aa`/`.ea` cert whose HashedId8 is not present in the latest
+ * stored CTL of any trusted Root CA. Prevents issuer certs orphaned by CTL
+ * rotation from accumulating. `dry_run` lists without deleting.
+ */
+void prune_ctl(const MainConfig& cfg, bool dry_run);
+
+// CLI subcommand tree.
+std::shared_ptr<CLI::App> build_prune_command(const MainConfig&);
+
+} // namespace pki
+} // namespace vanetza