feat(session): list and detail JSON API with filters

feat(ingest): NDJSON ingest with chunked transactions and partial-accept

feat(auth): forward-auth + OIDC bearer middleware with shared allowlist

feat(http): chi server with middleware stack + RFC 7807 problem renderer

feat(platform): scribe logger, prometheus registry, health checker set

feat(db): SQLite schema with FTS5 + migration runner

feat(config): viper-loaded config with fail-fast validation

feat: bootstrap lethe server skeleton + wire contract