Delegate Orrery graph reads to microcosm-local-provider #3

Move browser document loading and completed-publication/evidence reads to the provider TypeScript package. Retain React UI, Next routes, authorization, immutable write endpoints, Blob adapters and credentials in this repository. Stack a draft consumer PR on #1. Implement and test now; defer merge and activation until PolicyEngine/microcosm-emitter#4 is merged and its npm package is published. Pin exact provider source for draft tests; switch to registry version and regenerate lockfile before merge. Calibration dashboard telemetry is out of scope.