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FLASHING.md says how to take a newer version of the colleague's tree (copy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/docs/idf/evidence/security-device-07/console.txt

@@ -0,0 +1,17 @@
+-- test_trust_domain_and_pool (free heap 111944, largest block 81920)
+-- test_signing_profiles (free heap 111676, largest block 81920)
+-- test_fail_closed (free heap 111676, largest block 81920)
+-- test_fail_closed: unknown issuer (free heap 111676, largest block 81920)
+-- test_fail_closed: expired ticket (free heap 111676, largest block 81920)
+-- test_fail_closed: SN-DECAP (free heap 111676, largest block 81920)
+-- test_identifier_change (free heap 111676, largest block 81920)
+-- test_gn_core_identifier_change (free heap 111676, largest block 81920)
+-- test_sf_facilities_hook (free heap 111676, largest block 81920)
+-- test_verification (free heap 111676, largest block 81920)
+-- verification cost: certificate-signed 35480 us (chain + message), digest-signed 35054 us (message only), ECDSA verify alone 29778 us
+-- test_chain_consistency (free heap 111676, largest block 81920)
+-- test_region_consistency (free heap 111448, largest block 63488)
+-- test_ecies (free heap 110616, largest block 31744)
+-- test_enrolment_and_authorization (free heap 110616, largest block 31744)
+PASS: 747 checks (host/component tests, not ETSI ATS verdicts)
+VIDF_TEST_RESULT=0

microbu-esp32c5/external/vanetza-idf/docs/idf/evidence/security-device-07/result.json

@@ -0,0 +1,14 @@
+{
+  "kind": "component-tests",
+  "target": "esp32c5",
+  "idf_version": "6.0.2",
+  "port": "COM11",
+  "status": "pass",
+  "reset": "none",
+  "checks": 747,
+  "backend": "BackendMbedTls (PSA Crypto, mbedTLS 4.1.0 of ESP-IDF 6.0.2) with CONFIG_MBEDTLS_HARDWARE_ECDSA_VERIFY; 747 checks = 873 host checks minus the OpenSSL-only oracle tests",
+  "capture": "listen-only after the esptool post-flash reset",
+  "verifies": "receive-side verification (test_verification), the IEEE Std 1609.2 clause 5.1.2 chain consistency (test_chain_consistency) and the clause 6.4.17 region consistency under an identifiedRegion root (test_region_consistency) on the device; verification cost line: certificate-signed 35.5 ms, digest-signed 35.1 ms end to end, raw ECDSA P-256 verify 29.8 ms on the ECDSA peripheral",
+  "note": "the same checks appended to test_verification failed on the device only: with a fourth receiver trust configuration the heap was too fragmented (largest free block 16 kB) and an allocation failure inside verify() surfaced as INCOMPATIBLE_PROTOCOL through the catch-all; the chain and region scenarios therefore run as their own tests with a fresh heap and at most two stations alive",
+  "sha256": "20abb00efc091b27e7d43bf040967ffd808ca5a5e07d9ec6f0d3d9bee3cef7ec"
+}