EPIC: Reliability and production readiness

## Summary
Epic for reliability and production-readiness work in RFChat.

## Child Themes
- Reconnect correctness, realtime consistency, and scaling.
- Performance, observability, jobs, storage, backup, and restore.
- Session/security surfaces and deployability for self-hosted operators.

## Notes
- This epic should stay high-level; detailed scope belongs in child task issues.

Use this epic as an index for the child task issues rather than as an implementation starting point; it names no files, tests, or entry points. Begin by locating or creating focused issues for reconnects, scaling, observability, jobs, storage, backup, restore, sessions, security, and deployment, with completion criteria defined in each child issue.

Written by the indexing model from the issue text.