migrate 392 questions to pattern format

backend/data/questions/ipo.yaml

@@ -8,8 +8,10 @@ categories:
   - heap
   - sorting
 patterns:
-  - heap
-  - greedy
+  - slug: greedy
+    is_optimal: true
+  - slug: heap
+    is_optimal: false
 
 function_signature: "def find_maximized_capital(k: int, w: int, profits: list[int], capital: list[int]) -> int:"