docs: update exposure and pairing guidance

[Aaronontheweb]

Summary

• add reverse-proxy guidance to the exposure and security docs, including trusted proxy requirements and non-loopback final-hop rules
• update pairing, Docker, and init docs to explain first-launch bootstrap seeding, daemon-host recovery flows, and bearer auth behavior in non-local modes
• refresh the generated social image manifest for the updated exposure modes page

Testing

• npm run build