Add Docker, bash launcher, and Linux-first README

Lets the project be served as a web app from a Linux host in one command:
- Dockerfile (python:3.12-slim + non-root user + streamlit healthcheck)
- docker-compose.yml with env_file, restart policy, configurable HOST_PORT,
  and an optional CA-bundle volume for self-signed GPFS GUIs
- .dockerignore to keep the image lean
- run.sh for native (non-Docker) runs: creates a venv on first use and
  launches either the Streamlit UI (default) or the REPL
- .gitattributes pins LF line endings on shell/yaml/py so scripts stay
  executable when checked out on Linux from a Windows host
- README rewritten with Linux/Docker quick starts in front, Windows behind

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,31 @@
+FROM python:3.12-slim AS base
+
+ENV PYTHONDONTWRITEBYTECODE=1 \
+    PYTHONUNBUFFERED=1 \
+    PIP_DISABLE_PIP_VERSION_CHECK=1 \
+    PIP_NO_CACHE_DIR=1 \
+    STREAMLIT_SERVER_ADDRESS=0.0.0.0 \
+    STREAMLIT_SERVER_PORT=8501 \
+    STREAMLIT_SERVER_HEADLESS=true \
+    STREAMLIT_BROWSER_GATHER_USAGE_STATS=false
+
+WORKDIR /app
+
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends curl ca-certificates \
+ && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt ./
+RUN pip install -r requirements.txt
+
+COPY gpfs_agent ./gpfs_agent
+
+RUN useradd --create-home --uid 10001 app && chown -R app:app /app
+USER app
+
+EXPOSE 8501
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=15s --retries=3 \
+    CMD curl -fsS http://localhost:8501/_stcore/health || exit 1
+
+CMD ["streamlit", "run", "gpfs_agent/web.py"]