migrate 392 questions to pattern format

backend/data/questions/01-matrix.yaml

@@ -7,9 +7,12 @@ categories:
   - arrays
   - graphs
 patterns:
-  - bfs
-  - matrix-traversal
-  - dynamic-programming
+  - slug: bfs
+    is_optimal: true
+  - slug: matrix-traversal
+    is_optimal: false
+  - slug: dynamic-programming
+    is_optimal: false
 
 function_signature: "def update_matrix(mat: list[list[int]]) -> list[list[int]]:"