`EventBuilder` could set weights and nothing else, so `prior` and
`drift_scale` were reachable only through the typed
`Event`/`Team`/`Member` shape plus `add_events`. Which ingestion route a
competitor arrived through decided whether it could be configured.
`members(...)` takes `Member` values directly, so `Member`'s own builder
expresses everything. `team(...)` stays the common case.
One escape hatch rather than `priors` and `drift_scales` setters beside
`weights`, as the issue suggested and then argued against itself: a
parallel array per field means a parallel length check per field, and
each one is a new way to get the lengths wrong. `Member` already has a
builder; this just lets the fluent path reach it.
`record_winner`/`record_draw` are deliberately left alone. They are the
two-argument convenience path, and extending them would be a breaking
signature change. The issue's reason for wanting them extended has also
weakened: it said a competitor arriving through them was "permanently
stuck on the history defaults", and since 8c087ad that is no longer true
— a later `add_events` carrying the `Member` refits the whole history.
Measured, late configuration through that route reaches mu 40.000000000,
identical to configuring from the start.
Refs #37
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
