fix: Docker build now compiles submodules correctly

- Remove .gitmodules from .dockerignore so the build loop can discover
  which directories to compile
- Add git to Dockerfile apt installs (needed for git config --file parsing)
- Gate git submodule update --init on .git presence, not .gitmodules;
  the compile loop still runs in Docker since .gitmodules is now present
- hashcat skipped in Docker build loop since system hashcat is in PATH

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile.test

@@ -7,6 +7,7 @@ RUN apt-get update \
         build-essential \
         ca-certificates \
         curl \
+        git \
         gzip \
         hashcat \
         ocl-icd-libopencl1 \