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/docs/idf/evidence/security-device-06/console.txt

@@ -0,0 +1,15 @@
+-- test_trust_domain_and_pool (free heap 112008, largest block 81920)
+-- test_signing_profiles (free heap 111700, largest block 81920)
+-- test_fail_closed (free heap 111700, largest block 81920)
+-- test_fail_closed: unknown issuer (free heap 111700, largest block 81920)
+-- test_fail_closed: expired ticket (free heap 111700, largest block 81920)
+-- test_fail_closed: SN-DECAP (free heap 111700, largest block 81920)
+-- test_identifier_change (free heap 111700, largest block 81920)
+-- test_gn_core_identifier_change (free heap 111700, largest block 81920)
+-- test_sf_facilities_hook (free heap 111700, largest block 81920)
+-- test_verification (free heap 111700, largest block 81920)
+-- verification cost: certificate-signed 34664 us (chain + message), digest-signed 34612 us (message only), ECDSA verify alone 29666 us
+-- test_ecies (free heap 111108, largest block 81920)
+-- test_enrolment_and_authorization (free heap 111108, largest block 81920)
+PASS: 668 checks (host/component tests, not ETSI ATS verdicts)
+VIDF_TEST_RESULT=0

obu-firmware/external/vanetza-idf/docs/idf/evidence/security-device-06/result.json

@@ -0,0 +1,18 @@
+{
+  "kind": "component-tests",
+  "target": "esp32c5",
+  "idf_version": "6.0.2",
+  "port": "COM11",
+  "status": "pass",
+  "reset": "none",
+  "checks": 668,
+  "backend": "BackendMbedTls (PSA Crypto, mbedTLS 4.1.0 of ESP-IDF 6.0.2) with CONFIG_MBEDTLS_HARDWARE_ECDSA_VERIFY; 668 checks = 794 host checks minus the OpenSSL-only oracle tests",
+  "capture": "listen-only after the esptool post-flash reset",
+  "verifies": "receive-side verification (test_verification) on the device; verification cost line: digest-signed message 34.6 ms end to end, raw ECDSA P-256 verify 29.7 ms on the ECDSA peripheral (control build without the peripheral: 57.6 ms raw, 62 ms end to end, not retained)",
+  "sha256": {
+    "application": "2a14764ceb3062010f9d466b80a1a2dbd178611d52adf8dc479d5933d82e32a4",
+    "bootloader": "93903cefa2bae3f5805a604ae744fabfdea78a866a1230ec3cc129190b93fe40",
+    "partition_table": "73c0b5c3e5fcba3a151cc70c453c93dd5f4798899e7f2f8cca76da1f32ffc501",
+    "sdkconfig": "e793777a0f878c17d97d1a34de6c9a136b9239b52cb23d17874790951b4bd752"
+  }
+}