NS-18: InteractionRequest, client prototype, Postgres test UX
Server: POST /game/players/{id}/interact, HorizontalReach, prototype registry, DTOs, tests; default spawn (-5,0.9,-5); dev HttpLogging.
Client: terminal, radius glow preview, interaction_request_client (interact/E), main wiring; obstacle moved off center.
Tests: postgres.runsettings, launchSettings, Docker compose auto-start/teardown harness, async-safe init.
Docs: plan AC, E1.M1 snapshot, alignment table, server/client README, code review 2026-04-04.