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>

docker-compose.yml

@@ -0,0 +1,15 @@
+services:
+  gpfs-agent:
+    build: .
+    image: gpfs-agent:latest
+    container_name: gpfs-agent
+    restart: unless-stopped
+    ports:
+      - "${HOST_PORT:-8501}:8501"
+    env_file:
+      - .env
+    # Uncomment to mount a custom CA bundle and tell the app to use it.
+    # volumes:
+    #   - ./certs:/certs:ro
+    # environment:
+    #   GPFS_CA_BUNDLE: /certs/ca.pem