By Gus Trompiz and Pavel Polityuk PARIS/KYIV (Reuters) – Ukraine has managed to boost its Black Sea grain exports to a level not seen since before Russia’s invasion, although the Red Sea shipping crisis poses a new challenge to its crucial agricultural trade. Kyiv’s success in replacing a UN-backed Black Sea export deal with its own shipping scheme has brought relief for Ukrainian farmers and importing countries while representing a naval breakthrough for Ukraine’s military as a land counteroffensive has stalled. The export turnaround helped Ukraine’s economy to steady last year and further ta…