feat: option lab

backend/services/option_chain.py

@@ -35,6 +35,9 @@ def get_chain_slice(
     really was on a position's entry_date, not today's. Every days-to-expiry figure is
     computed relative to `as_of` in that case, not date.today() — using today's date to
     size a historical chain would silently misdate every contract in it.
+
+    A bare date (no time component) in `as_of` is handled by get_snapshot_rows_asof itself
+    (treated as end-of-day, not start — see its docstring for why that matters).
     """
     from services.database import get_latest_saxo_snapshot_rows, get_snapshot_rows_asof