Upload a CSV or Excel file of historical IV data into iv_daily_snapshot.

Accepts files from any source — ORATS, Market Chameleon, AlphaQuery VolVue, OptionSlam, or any custom spreadsheet.

Required columns (flexible naming):

• ticker / symbol / underlying
• date / trade_date / snapshot_date

Optional columns (auto-detected):

• iv / iv30 / weightedImpliedVolatility
• iv_rank / ivRank / impliedVolatilityRank1y
• iv_percentile / ivPercentile
• put_call_ratio / pcr
• total_oi / openInterest
• sector / industry

IV values > 5 are auto-converted from percentage to decimal (e.g. 42.0 → 0.420). Duplicate (ticker, date) rows within the file are merged before the write. The write replaces the stored row, so a column this file omits is cleared — upload complete rows, not partial ones.

Returns: { parsed, upserted, skipped, warnings, sources_detected }