feat: renumber bullet lists

[dkarter]

Motivation

Implements RMS-71 by making RenumberList and RenumberSelection normalize ordered bullet markers while preserving standard bullets and checkbox text.

Linear: RMS-71

Summary of Changes

• Added ordered-list renumbering for cursor-contained lists and visual ranges.
• Reset nested ordered counters when returning to parent levels.
• Preserved standard bullets/checklist text and respected line spacing/wrapped continuations.
• Enabled the renumbering specs covered by this ticket.

Testing

• mise run fmt:check
• mise run test

Dependencies/Special Considerations

Stacked on PR #11 / dorian/rms-72-implement-outline-promotion-and-demotion.

Stack

1. feat: add neovim lua plugin scaffold #6
2. feat: continue standard bullets #4
3. feat: support ordered bullet continuations #7
4. feat: support wrapped and document bullets #9
5. feat: handle empty bullets and spacing #10
6. feat: support outline promotion #11
7. feat: renumber bullet lists #12 👈 current
8. feat: support nested checkboxes #13
9. chore: add release please #14
10. docs: add lazy.nvim usage #15