Wire IPositionStateStore to Npgsql when ConnectionStrings:NeonSprawl is set,
with versioned DDL under server/db/migrations and a shared PostgresPositionBootstrap
for schema plus dev-player seeding at host startup. In-memory tests override Postgres
registrations when CI sets the connection string globally.
Add GitHub Actions Postgres service for dotnet test, server README updates,
decomposition and implementation-plan docs, code review write-up, and C# brace
conventions in csharp-style rule.
VinPropane