Separate observed chart sensitivity across time and location uncertainty

Resolves one exact civil center instant, then evaluates a fixed full-factorial matrix of seven exact UTC instants and nine coordinates: the supplied center plus eight equal bearings on a caller-declared radius. For Ascendant and Midheaven signs, all twelve cusp signs, and selected-planet signs and houses, it reports observed time-axis, location-axis, combined, and interaction-only variation with traceable sample assignments. This is a bounded sampled envelope, not birth-time rectification, a continuous-time proof, a guarantee over the full location disk, statistical confidence, causal attribution, ranking, interpretation, or prediction. Gauquelin is excluded because it is a 36-sector system. 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.