Update a condition card's parameters. Merges updates and recompiles.

The shape of updates depends on how the card was built (check with builder_get_strategy / builder_discover if unsure):

• Smart card (e.g. trailing_stop, ma_crossover): pass the smart-card params to change, e.g. {"atr_mult": 2.5}.
• Raw condition (e.g. compare, cross, band_edge): pass the flat Condition fields, e.g. {"rhs": 40, "op": ">="}.
• Combinator (allOf/anyOf/not/sequence): update its own fields; to change a child, update that child card by its own card_id instead.

Only the keys you pass change; the rest are preserved. The card is recompiled, so an update producing an invalid condition is rejected.