migrate 392 questions to pattern format

backend/data/questions/combination-sum-iv.yaml

@@ -7,7 +7,8 @@ categories:
   - dynamic-programming
   - arrays
 patterns:
-  - dynamic-programming
+  - slug: dynamic-programming
+    is_optimal: true
 
 function_signature: "def combination_sum4(nums: list[int], target: int) -> int:"