Make the chutney: Combine the cilantro, mint, coconut milk, lime juice, jalapeño, garlic, sugar and 1/2 teaspoon salt in a blender; puree until smooth. Transfer to a bowl, cover with plastic wrap and refrigerate until ready to serve or up to 1 day.
Prepare the kebabs: Melt the butter in a small skillet over medium heat. When it foams, stir in the garlic, cumin, coriander, paprika and 1/2 teaspoon salt; cook, stirring, 4 minutes. Remove the spiced butter from the heat and let cool. (The butter can be made up to 1 day in advance.)
Preheat a grill to medium. If using wooden skewers, soak them in water, about 15 minutes (you'll need 4 to 6 skewers). Thread the scallops and zucchini rounds onto the skewers. Brush the grill generously with vegetable oil. Stir the spiced butter, then brush on the kebabs and season with salt. Grill the kebabs until the scallops are firm and just cooked through and the zucchini is marked, 3 to 4 minutes per side. Brush with more spiced butter. Serve with the chutney and lime wedges.