Export ./stream and ./persistence subpaths (room-name codecs, isAwarenessRoom, Persistence) for integrators

[bgeils]

Summary

The package exports only ., ./plugins/s3, and ./package.json. Integrators who operate y/hub in production end up needing a handful of internals, and today the only options are deep source imports (break on package layout changes) or re-implementing formats byte-for-byte (break silently on format changes). Concretely, we currently need:

• isAwarenessRoom(room) — we special-case awareness rooms in admin tooling and worker policy (see Awareness-only rooms grow without bound when compaction stops — add write-time MAXLEN caps / first-class ephemeral rooms #64).
• encodeRoomName / decodeRoomName / encodeQuarantineName — admin/ops tooling that lists streams, inspects quarantines, and reconciles lost compact tasks must reproduce the key formats; v0.7.0's uriEncode (escaping !'()*) is exactly the kind of change that silently breaks a hand-rolled copy.
• A ./persistence subpath exporting Persistence — we pin regression tests against the store SQL's idempotency (ON CONFLICT presence) so a future regression to a plain INSERT fails in CI instead of production.
• A ./stream subpath (Stream + the name codecs) for integration tests that exercise the stream layer against real Redis.

Ask

Add ./stream and ./persistence export subpaths and export the room-name codecs + isAwarenessRoom from the root. Happy to send the PR — it is package.json exports plus re-exports, no behavior change.