Convert persistence and the local service to strict TypeScript #27

Outcome

Review persistence, migration, metadata discovery, settings storage, and the loopback service share checked contracts across every boundary.

Stack position

3 of 7 — stacked on the typed review domain.

Acceptance criteria

• Review and settings stores, migration, metadata discovery, endpoint, client, and service modules are converted.
• Filesystem, JSON, HTTP, and persisted inputs enter typed code as unknown and pass through existing validators.
• Storage formats, loopback protocol behavior, and failure semantics remain unchanged.
• Corresponding tests are converted in the same PR.
• No untracked type escape hatches are introduced.
• The temporary JavaScript boundary shrinks and all checks pass.