Sorry about the ich.
Heat and salt help a lot with ich, and do not affect (much) plants, except for extremely delicate ones (rather the exception than the rule), and do not affect snails at all.
Also, typical products that include malachite green CAN be used successfully in planted tanks, and even in nail containing tanks. Again, the plants are affected only minimally. At least this has been mt experience.
If the snails are ornamental, take them out into a different container while the treatment proceeds. They can returned to display tanks later after a precautionary period, as they are not carriers of the parasite (if well washed and some time wait time exercised). If the snails are not ornamental, then there are of no interest themselves and good ridance! It is a matter of deciding on priorities.