Event/message store used by the Eventide project. Implemented as a single table on top of PostgreSQL, shipped as a Ruby gem with a CLI (e.g. `create db`) that sets up sensible defaults. The table stores: global_position (a global message sequence starting at 0), position (sequence within a single stream), time, stream_name, type (message class, e.g. 'AddLineItem'), data (JSON of message attributes), metadata (JSON with causation/correlation info), and a UUID message id. Exposes an interactive test CLI for writing commands from the shell and a web viewer that lists command/event streams and their messages. Because it's just Postgres, the only prerequisite to start event sourcing in Ruby is having Postgres installed.