Reset all design state when submission succeeds

Clear not just elements but also color, size, dimensions, quantity,
and image dimensions so a fresh canvas is guaranteed after submission.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/components/DesignCanvas.tsx

@@ -962,10 +962,16 @@ export default function DesignCanvas({ product, isAdminEditing = false }: { prod
           setDesignApprovalId(design.id);
           setApprovalStatus('PENDING');
           setSubmissionMessage(`✓ Design submitted for approval! You'll receive an email when it's ready to add to your bag.`);
-          // Clear design elements so user can start fresh
+          // Clear design elements and state so user can start fresh
           setElementsFront([]);
           setElementsBack([]);
-          // Save to localStorage so status persists on page reload
+          setColor(product.colors[0]);
+          setSize(product.sizes[0] ?? null);
+          setDesignWidthCm(null);
+          setDesignHeightCm(null);
+          setQuantity(1);
+          setImageDimensions({});
+          // Clear localStorage draft and save approval status
           if (typeof window !== 'undefined') {
             localStorage.removeItem(`designDraft_${product.id}`);
             localStorage.setItem(`designApproval_${product.id}`, JSON.stringify({