refactor: avoid parsing document twice for figure numbers

renderer/document.py

@@ -2,6 +2,9 @@ import mistletoe
 
 
 class Document(mistletoe.Document):
-    # margin_count = 0
-    # margin_anchor_count = 0
-    references = {}
+    def __init__(self, *args, **kwargs):
+        # references must exist before super().__init__ tokenizes the lines,
+        # since ReferencedToken reads it from _root_node during tokenization.
+        self.references: dict[str, str] = {}
+
+        super().__init__(*args, **kwargs)