Fetch the published vectors in CI - the split removed the sibling they lived in

The engine job failed on its first real run: PublishedVectorsTest and
AccountKdfTest search sibling checkouts for the canonical vector files, and the
standalone repository has no ../../engine and no flamenet-e2e clone beside it
on a runner. Both tests already honour an env override, so CI fetches both
files from flamenet-e2e at HEAD and points the tests at them.

Deliberately NOT a copied vector file in this repo: a copy drifts, and an
engine tested against its own copy has quietly stopped being tested against
the published ones. The job now fails if flamenet-e2e is unreachable, which is
the correct failure - an engine that cannot see the vectors must not report
green.

Verified by reproducing CI locally: standalone checkout, env vars only,
:engine:test passes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitlab-ci.yml

@@ -39,10 +39,27 @@ variables:
 
 # The protocol, against the same published vectors the JS and Swift engines are
 # held to. No SDK, no emulator, no device.
+# 🔴 **The vectors live in flamenet-e2e, and this repo does not carry a copy.**
+# That is deliberate — a copied vector file is one that drifts, and an engine
+# tested against its own copy has quietly stopped being tested against the
+# published ones. The test searches sibling checkouts and honours
+# FLAMENET_VECTORS; in CI there are no siblings, so the pipeline fetches the
+# file from the canonical repository at HEAD and points the tests at it.
+#
+# ⚠️ This makes the job fail if flamenet-e2e is unreachable, and that is the
+# correct failure: an engine that cannot see the vectors must not report green.
 engine:
   <<: *rules
   stage: test
   image: gradle:9-jdk21
+  variables:
+    FLAMENET_VECTORS: /tmp/protocol-v1.json
+    FLAMENET_ACCOUNT_VECTORS: /tmp/account-kdf-v1.json
+  before_script:
+    - curl -fsSL -o "$FLAMENET_VECTORS"
+        "https://gitlab.com/paulhitt/flamenet-e2e/-/raw/main/test/vectors/protocol-v1.json"
+    - curl -fsSL -o "$FLAMENET_ACCOUNT_VECTORS"
+        "https://gitlab.com/paulhitt/flamenet-e2e/-/raw/main/test/vectors/account-kdf-v1.json"
   script:
     - gradle :engine:test