extend Steps ntuple and switch Docker to Geant4 submodule source

Add 15 new columns to the Steps ntuple: edep, step_length, parent_id,
process name, layer_id, material, pre-step momentum direction, and
B/E field components (in T and V/m) at the pre-step point.

Replace wget Geant4 tarball download in all three Dockerfiles with
ADD of the lib/geant4 submodule source; narrow submodule init to
lib/pybind11 only so builds no longer require network access for Geant4.

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

docker/Dockerfile-cpu

@@ -50,22 +50,24 @@ RUN mkdir dawn-source \
     && make clean && make guiclean && make && make install \
     && cd - && rm -rf "dawn-source"
 
-## main package
+## main package — build Geant4 from submodule source
+ADD minicalosim/lib/geant4 /tmp/geant4-src
 
-RUN cd && wget -q https://gitlab.cern.ch/geant4/geant4/-/archive/v11.1.2/geant4-v11.1.2.tar.gz && \
-    tar -xzf geant4-v11.1.2.tar.gz -C /tmp && \    
-    mkdir /tmp/geant4-v11.1.2-build && \
-    cd /tmp/geant4-v11.1.2-build && \
-    cmake -DCMAKE_INSTALL_PREFIX=/opt/geant4-v11.1.2 -DCMAKE_RULE_MESSAGES=OFF -DGEANT4_INSTALL_DATA=ON \
-    -DGEANT4_USE_GDML=ON -DGEANT4_USE_OPENGL_X11=ON \
-             -DGEANT4_BUILD_MULTITHREADED=ON \
-             -DGEANT4_BUILD_TLS_MODEL=global-dynamic \
-    -DGEANT4_USE_RAYTRACER_X11=ON /tmp/geant4-v11.1.2 >/dev/null && \
-    make -j4 >/dev/null && \
-    make install >/dev/null
-
-RUN rm -rf /tmp/geant4-v11.1.2 && \
-    rm -rf /tmp/geant4-v11.1.2-build
+RUN cmake \
+        -S /tmp/geant4-src \
+        -B /tmp/geant4-build \
+        -DCMAKE_INSTALL_PREFIX=/opt/geant4-v11.1.2 \
+        -DCMAKE_RULE_MESSAGES=OFF \
+        -DGEANT4_INSTALL_DATA=ON \
+        -DGEANT4_USE_GDML=ON \
+        -DGEANT4_USE_OPENGL_X11=ON \
+        -DGEANT4_BUILD_MULTITHREADED=ON \
+        -DGEANT4_BUILD_TLS_MODEL=global-dynamic \
+        -DGEANT4_USE_RAYTRACER_X11=ON \
+        >/dev/null && \
+    cmake --build /tmp/geant4-build --parallel $(nproc) >/dev/null && \
+    cmake --install /tmp/geant4-build >/dev/null && \
+    rm -rf /tmp/geant4-src /tmp/geant4-build
 
 
 RUN python3 -m pip install geant4-pybind
@@ -94,7 +96,8 @@ ARG USER
 ADD minicalosim /root/minicalosim
 
 RUN cd  /root/minicalosim && git checkout $COMMIT && \
-    mkdir -p build && cd build && rm -rf * && cmake ../ && make -j4 &&\  
+    git submodule update --init lib/pybind11 && \
+    mkdir -p build && cd build && rm -rf * && cmake ../ && make -j$(nproc) &&\
     cp minicalo* ../bind/G4Calo.py /usr/local/lib/python3.8/dist-packages/