fix(docker): add missing COPY data/ directive

Fixes #3063

The Dockerfile was missing the COPY directive for the data/ directory,
which contains security/attack-corpus-v1.jsonl required by the
semantic guard feature via include_str!() at compile time.

This caused Docker builds to fail with:
  error: couldn't read src/security/../../data/security/attack-corpus-v1.jsonl

Risk: low (build fix only, no runtime behavior change)

Dockerfile

@@ -31,6 +31,7 @@ COPY src/ src/
 COPY benches/ benches/
 COPY crates/ crates/
 COPY firmware/ firmware/
+COPY data/ data/
 COPY web/ web/
 # Keep release builds resilient when frontend dist assets are not prebuilt in Git.
 RUN mkdir -p web/dist && \