feat: ETL steps for planets and moons

[GitAddRemote]

Summary

• PlanetsSyncStep — fetches `/planets`, validates `star_system_uex_id` FK (hard skip on missing), guards `orbit_uex_id`, `faction_uex_id`, and `jurisdiction_uex_id` with warn+null, upserts `station_planet` on `uex_id`
• MoonsSyncStep — fetches `/moons`, validates `star_system_uex_id` and `planet_uex_id` FKs (hard skip on either missing), guards `orbit_uex_id`, `faction_uex_id`, and `jurisdiction_uex_id` with warn+null, upserts `station_moon` on `uex_id`
• Both steps registered in `CatalogEtlModule` and `CatalogEtlService` at tier-4 (after orbits), consistent with dependency order
• `CatalogEtlService` spec updated with mock providers for both new steps

Test plan

• 27 new unit tests across 3 spec files — all passing locally
• TypeScript typecheck passes (backend + frontend)
• Lint/Prettier clean (enforced by pre-commit hook)
• After ETL run: `SELECT count(*) FROM station_planet` matches UEX count
• After ETL run: `SELECT count(*) FROM station_moon` matches UEX count
• Planet/moon with unknown star system appears in `station_etl_warning` and is absent from its table
• Planet/moon with unknown orbit is present with `orbit_uex_id = NULL` and a warning row

Closes #192

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