upstream firehose seq numbers exceed i64 max — switch all seq types to u64 across subscriber, broadcaster, ring_buffer, and event_log. SQLite storage uses XOR-with-sign-bit encoding to preserve ordering. update zat dependency to v0.2.7 (adds cbor.getUint). also: bind WebSocket server to 0.0.0.0 (was 127.0.0.1, unreachable in k8s), add /favicon.svg route. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>