migrate 392 questions to pattern format

backend/data/questions/check-if-string-is-a-prefix-of-array.yaml

@@ -7,7 +7,8 @@ categories:
   - arrays
   - strings
 patterns:
-  - two-pointers
+  - slug: two-pointers
+    is_optimal: true
 
 function_signature: "def is_prefix_string(s: str, words: list[str]) -> bool:"