The prototype uses max_size for the range metadata field. We should verify this name is clear and consistent with WiredTiger conventions, and add documentation for the augmented skiplist design.

Tasks

• src/include/block.h — Review max_size field naming: consider alternatives like max_extent_size, span_max_size, subtree_max (criterion: name chosen and documented in WT_EXT structure comment)
• src/block/block_ext.c — Add a block comment at the top of the file documenting the augmented skiplist design: what max_size represents, how it enables O(log n) search, invariants maintained (criterion: comment explains design to a reviewer unfamiliar with the prototype)
• src/block/block_ext.c — Document __block_first_srch_v2 algorithm: explain skiplist traversal strategy, how max_size is used to skip spans (criterion: function comment describes algorithm)
• src/block/block_ext.c — Ensure update_max_size has a clear comment explaining when it's called and what it does (criterion: comment explains purpose and calling context)

Files to create or modify

• src/include/block.h — structure definitions and field comments
• src/block/block_ext.c — algorithm documentation

Definition of Done

• max_size naming reviewed and finalized (keep current name or choose better alternative)
• Augmented skiplist design documented at file and function level
• Code is reviewable by engineers unfamiliar with the prototype