Add a conversion-settlement/freshness flag and clearer date-basis labeling to the Google Ads connector#1788

Google data also extracts correctly — you already expose both conversions_value (credited to the interaction/click date, which keeps it aligned with spend for correct daily ROAS) and conversions_value_by_conversion_date (credited to the actual sale date).
The gap is purely operational: (a) please add a per-day settlement/freshness indicator (or document the stabilization window) so we can flag days whose interaction-date conversions are still filling in retroactively and re-pull them, rather than freezing early values; and (b) make the date-basis explicit in the field metadata — clearly tag which metrics are interaction-date vs conversion-date — so an automated pipeline never accidentally mixes a conversion-date value with interaction-date cost (which silently breaks daily ROAS).
No new metrics are needed; this is about a freshness signal and unambiguous labeling.