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/vanetza/geodesy/CMakeLists.txt

@@ -0,0 +1,48 @@
+add_vanetza_component(geodesy
+    country_data_reader.cpp
+    country_database.cpp
+    geodesy.cpp
+    haversine.cpp
+)
+
+if(VANETZA_WITH_GEOGRAPHICLIB)
+    target_sources(geodesy PRIVATE geographiclib.cpp)
+    target_link_libraries(geodesy PRIVATE GeographicLib::GeographicLib)
+    target_compile_definitions(geodesy PUBLIC VANETZA_WITH_GEOGRAPHICLIB)
+endif()
+
+if(VANETZA_EMBED_COUNTRY_DATA)
+    find_program(UV_EXECUTABLE uv REQUIRED)
+    set(VANETZA_COUNTRY_DATA_RESOLUTION "50m" CACHE STRING
+        "Natural Earth resolution for country data (110m, 50m, 10m)")
+    set_property(CACHE VANETZA_COUNTRY_DATA_RESOLUTION PROPERTY STRINGS 110m 50m 10m)
+
+    set(_tool_dir "${PROJECT_SOURCE_DIR}/tools/country-data")
+    set(_country_bin "${CMAKE_CURRENT_BINARY_DIR}/country_data.bin")
+    set(_embedded_cpp "${CMAKE_CURRENT_BINARY_DIR}/country_data_embedded.cpp")
+
+    add_custom_command(
+        OUTPUT "${_country_bin}"
+        COMMAND "${UV_EXECUTABLE}" run "${_tool_dir}/convert.py"
+            --resolution "${VANETZA_COUNTRY_DATA_RESOLUTION}"
+            --output "${_country_bin}"
+        DEPENDS "${_tool_dir}/convert.py"
+        COMMENT "Converting Natural Earth ${VANETZA_COUNTRY_DATA_RESOLUTION} to country data binary"
+        VERBATIM
+    )
+    add_custom_command(
+        OUTPUT "${_embedded_cpp}"
+        COMMAND "${UV_EXECUTABLE}" run "${_tool_dir}/embed.py"
+            --input "${_country_bin}"
+            --output "${_embedded_cpp}"
+        DEPENDS "${_country_bin}" "${_tool_dir}/embed.py"
+        COMMENT "Generating embedded country data source"
+        VERBATIM
+    )
+
+    target_sources(geodesy PRIVATE "${_embedded_cpp}")
+    target_link_libraries(geodesy PRIVATE common)
+    target_compile_definitions(geodesy PUBLIC VANETZA_WITH_EMBEDDED_COUNTRY_DATA)
+endif()
+
+add_test_subdirectory(tests)