Experiment: Refactored formatting code

[olehermanse]

From Claude:

1. Extracted named constants for repeated node type sets: INDENTED_TYPES, CLASS_GUARD_TYPES, BLOCK_TYPES
2. Extracted format_block_header() — the bundle/body header formatting logic that was inline in autoformat
3. Extracted needs_blank_line_before() — replaces the big if/elif chain for blank line insertion between children
4. Extracted get_comment_indent() — the comment indentation logic
5. Extracted is_empty_comment() — the bare # comment detection
6. Simplified the single-line promise path in autoformat by reusing can_single_line_promise() instead of duplicating
   its logic inline

[olehermanse]

This one is for review only, do not merge.

[larsewi]

Without diving too deep into the intricacies, I would say that this refactor makes the code more readable. It's easier to digest the smaller functions. Furthermore, the function names also help the reader reason about what is happening.

However, In many cases the docstrings just restates what the function names already clearly says. I think the docstring should convey information other than what is already obvious from the function name