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/hass/hass.service.j2

@@ -0,0 +1,18 @@
+[Unit]
+Description=Home Assistant
+After=network.target
+
+[Service]
+Type=simple
+User={{hass_user}}
+Group={{hass_group}}
+WorkingDirectory={{hass_directory}}
+ExecStart=/bin/bash -c 'source {{hass_directory}}/env/bin/activate && hass --config {{hass_directory}}'
+Restart=always
+RestartSec=3
+SyslogIdentifier=hass
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=multi-user.target