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/http.hpp

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <vanetza/common/byte_buffer.hpp>
+#include <boost/beast/http.hpp>
+#include <boost/optional/optional.hpp>
+#include <iosfwd>
+#include <stdexcept>
+#include <string>
+#include <utility>
+
+namespace vanetza
+{
+namespace pki
+{
+
+using HttpResponse = boost::beast::http::response<boost::beast::http::string_body>;
+
+struct HttpException : public std::runtime_error
+{
+    using std::runtime_error::runtime_error;
+
+    HttpException(const std::string& what, HttpResponse response) :
+        std::runtime_error(what), m_response(std::move(response))
+    {
+    }
+
+    // Server response associated with the failure, if any.
+    const boost::optional<HttpResponse>& response() const { return m_response; }
+
+private:
+    boost::optional<HttpResponse> m_response;
+};
+
+std::ostream& operator<<(std::ostream& os, const HttpException& e);
+
+struct HttpQuery
+{
+    static HttpQuery from_url(const std::string&);
+
+    bool secure = false;
+    std::string host;
+    std::string service;
+    std::string path;
+
+    const std::string& which_service() const;
+};
+
+/**
+ * \brief Resolve a (possibly relative) URL reference against a base URL per RFC 3986 §5.
+ *
+ * An empty reference yields the base unchanged. A reference carrying its own scheme
+ * (e.g. "https://...") is absolute and returned as-is. Otherwise it is resolved against
+ * the base: "//authority/..." replaces the authority, a leading-slash path replaces the
+ * base path, and any other path is merged onto the base's directory.
+ * \throws HttpException if the base URL cannot be parsed
+ */
+std::string resolve_url(const std::string& base, const std::string& reference);
+
+HttpResponse http_get(const HttpQuery& query);
+HttpResponse http_post(const HttpQuery& query, const std::string& content_type, const ByteBuffer& body);
+
+} // namespace pki
+} // namespace vanetza