Vendor the ASN.1 modules the codecs are verified against; untrack IDE churn

asn1/
Three tests assert exact bytes - CamEncodeGoldenTest, DenmAirReceiveTest and
SpatemUperCodecTest - and their expected values came from asn1tools compiled
against ETSI modules that existed only as an untracked working copy on one
machine. A golden-byte fixture nobody else can regenerate is a fixture nobody
can safely touch, so the modules are now in the repo.

Only the seven .asn files those tests need are copied, 576 KB of a 4.2 MB
checkout; the upstream Rust parser is not used by this project at all. Verified
sufficient in isolation: copied into an empty directory, all three specs compile
and reproduce the committed golden CAM bytes byte-identically.

Source is consider it GmbH's C-ITS-Parser (github.com/consider-it/C-ITS-Parser)
at f457426, MIT licensed - LICENSE is retained alongside as that requires. The
schemas themselves are ETSI's standard definitions; upstream's contribution is
assembling them into a compilable set. asn1/README.md records the provenance,
which module pairs with which message, and the rule that matters: never
regenerate a golden fixture from this project's own encoder, because sharing a
mistake between encoder and decoder is exactly the failure these files exist to
catch.

Doc references in the codecs and tests now point at asn1/ instead of the
untracked checkout, and C-ITS-Parser/ is gitignored so the working copy beside
the project is never picked up.

Untracked local state
- .idea/deploymentTargetSelector.xml rewrites itself on every deploy, so it has
  been showing as modified in essentially every commit. Along with
  deviceManager.xml, appInsightsSettings.xml and studiobot.xml it is per-machine
  state, not project configuration.
- obu-firmware/sdkconfig.old is ESP-IDF build output - it is the previous
  sdkconfig, rewritten on every build. sdkconfig.defaults remains tracked, since
  that is the configuration actually chosen.

All five stay on disk; only the tracking is removed. Also ignores
.claude/settings.local.json, which is per-machine, while leaving the skills
beside it committable as project knowledge.

app/src/test/java/com/hawhamburg/micr0bu/CamEncodeGoldenTest.kt

@@ -18,7 +18,7 @@ import org.junit.Test
  *
  * A round-trip test through this codebase's own decoder cannot catch that - it shares the
  * mistake. Only an independent implementation can. So the expected bytes below were produced by
- * `asn1tools` compiled from the real ETSI modules in the `C-ITS-Parser` checkout: it decoded this
+ * `asn1tools` compiled from the real ETSI modules in `asn1/`: it decoded this
  * encoder's output and re-encoded it, and the result was byte-identical to what is asserted here.
  * That is stronger than "it parses" - it means this encoder emits exactly what the reference
  * encoder emits.

app/src/test/java/com/hawhamburg/micr0bu/DenmAirReceiveTest.kt

@@ -24,7 +24,7 @@ import org.junit.Test
  *
  * ## Why the expected values can be trusted
  * Every asserted field was cross-checked against `asn1tools` decoding the same bytes with the real
- * ETSI modules from the `C-ITS-Parser` checkout (`denm_1_3_1.asn` + `cdd_1_3_1_1.asn`) — an
+ * ETSI modules in `asn1/` (`denm_1_3_1.asn` + `cdd_1_3_1_1.asn`) — an
  * independent implementation, not this codebase's own arithmetic. Across the full capture set that
  * cross-check agreed on all 1885 decodable DENMs, on every field below including `detectionTime`.
  *

app/src/test/java/com/hawhamburg/micr0bu/RsuCamDecodeTest.kt

@@ -17,7 +17,7 @@ import org.junit.Test
  *
  * The fixture is a real 26-byte RSU CAM taken live from the OBU's `v2x/rx/cam` topic; the
  * expected values are asn1tools' decoding of those same bytes using the ETSI modules in the
- * `C-ITS-Parser` checkout.
+ * `asn1/`.
  */
 class RsuCamDecodeTest {
 

app/src/test/java/com/hawhamburg/micr0bu/SpatemUperCodecTest.kt

@@ -20,7 +20,7 @@ import org.junit.Test
  * ## Why the expected values can be trusted
  * The bit layout was validated by replaying **79,042 real SPATEMs** - the whole drive across 7+
  * RSUs plus the live trigger - through a port of this decoder and comparing every field against
- * `asn1tools` decoding the same bytes with the ETSI modules from the `C-ITS-Parser` checkout.
+ * `asn1tools` decoding the same bytes with the ETSI modules in `asn1/`.
  * All 79,042 matched exactly, and none hit an unsupported branch. The values asserted below are
  * that independent decoder's output, not this codebase's own arithmetic.
  *