Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/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