Preflight every supported house system without fallback

Evaluates Cosmic Ephemeris's fixed 25-system house inventory for one exact birth geometry. Each system is reported as available or unavailable; successful cusp sets receive a deterministic fingerprint and geometrically undefined systems remain explicit failures. The route never substitutes a different house system, returns interpretations, or makes request-time network calls. One standard quota unit per admitted request; failed or timed-out admitted attempts are not refunded. Do not automatically retry. Historical mode uses an explicit BCE/CE date object and UT1 conventions. Its response is the versioned historical envelope, not the modern UTC envelope. Read result for calculation fields and metadata for limits and uncertainty.