docs: rewrite README with structured overview and quick start guide

Replaces the minimal project description with a comprehensive README
including a component overview table, quick start instructions, common
Ansible operations, and links to detailed documentation. Aligns with
Red Panda Approval™ standards.

ansible/jupyterlab/jupyterlab.service.j2

@@ -0,0 +1,34 @@
+[Unit]
+Description=JupyterLab Server
+After=network.target
+Wants=oauth2-proxy-jupyter.service
+
+[Service]
+Type=simple
+User={{ jupyterlab_user }}
+Group={{ jupyterlab_group }}
+WorkingDirectory={{ jupyterlab_notebook_dir }}
+
+ExecStart={{ jupyterlab_venv_dir }}/bin/jupyter-lab \
+    --config=/etc/jupyterlab/jupyter_lab_config.py \
+    --ip=127.0.0.1 \
+    --port={{ jupyterlab_port }} \
+    --no-browser \
+    --notebook-dir={{ jupyterlab_notebook_dir }}
+
+Environment="PATH={{ jupyterlab_venv_dir }}/bin:/usr/local/bin:/usr/bin:/bin"
+
+Restart=on-failure
+RestartSec=10
+
+# Security hardening
+NoNewPrivileges=true
+PrivateTmp=true
+
+# Logging
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=jupyterlab
+
+[Install]
+WantedBy=multi-user.target