Gate chart workflows against birth-time data quality

Classifies exact, approximate, or unknown birth-time input before a developer launches downstream chart workflows. Exact local times are resolved against pinned place and IANA data; repeated times retain both candidates and nonexistent times produce no facts. Approximate and unknown times expose explicitly sampled, non-exhaustive fact evidence while exact-chart routes remain blocked. The response never selects a representative time, rectifies a chart, ranks a convention, or returns statistical confidence. No request-time network access. 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.