Separate birth-time and convention sensitivity

Evaluates 22 sign and house facts over one shared UTC sample grid and two or three explicit convention profiles. Each fact is classified as stable, time-sensitive, convention-sensitive, or sensitive to both. Unknown time uses 25 samples across the complete local civil date; approximate time accepts symmetric 10–120 minute uncertainty in ten-minute increments. Results are sampled evidence, not statistical confidence, rectification, interpretation, prediction, or a ranking of conventions. 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.