Fix Rocq build: remove rocq-extraction (bundled in rocq-stdlib)

Extraction support is included via rocq-stdlib, which rocq-prover
already depends on. The rocq-extraction package does not exist in opam.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: cuihtlauac

rocq/Dockerfile

@@ -24,7 +24,7 @@ WORKDIR /home/vscode
 RUN opam switch ocaml && \
     eval $(opam env) && \
     opam update && \
-    opam install -y rocq-prover rocq-extraction
+    opam install -y rocq-prover
 
 # ============================================================================
 # Cleanup