refactor(infra): update Dockerfile and requirements for Streamlit app

when trying to deploy the copilot streamlit service, the image build
would fail because caltrans/pems:app was not available to the
AWS environment. So we now build the streamlit image just using its
own Dockerfile.

Author: lalver1

streamlit_app/Dockerfile

@@ -1,4 +1,33 @@
-FROM caltrans/pems:app
+ARG PYTHON_VERSION=3.12
+
+FROM python:${PYTHON_VERSION}
+
+ENV PYTHONDONTWRITEBYTECODE=1 \
+    PYTHONUNBUFFERED=1 \
+    USER=caltrans
+
+# create non-root $USER and home directory
+RUN useradd --create-home --shell /bin/bash $USER && \
+    # setup directories and permissions
+    mkdir -p /$USER/app && \
+    chown -R $USER:$USER /$USER
+
+# enter source directory
+WORKDIR /$USER
+
+COPY LICENSE app/LICENSE
+
+# switch to non-root $USER
+USER $USER
+
+# update env for local pip installs
+# see https://docs.python.org/3/using/cmdline.html#envvar-PYTHONUSERBASE
+# since all `pip install` commands are in the context of $USER
+# $PYTHONUSERBASE is the location used by default
+ENV PATH="$PATH:/$USER/.local/bin" \
+    PYTHONUSERBASE="/$USER/.local"
+
+WORKDIR /$USER/app
 
 ENV PYTHONPATH="$PYTHONPATH:/$USER/app"
 

streamlit_app/requirements.txt

@@ -1,3 +1,4 @@
+django==5.1.6
 pandas==2.2.3
 pygwalker==0.4.9.15
 streamlit==1.44.1