[audit] Nvim 0.13 repurposes the unmapped default `Q` for multicursor, not macro replay

[stanfish06]

What

Nvim HEAD's runtime/doc/news.txt (BREAKING CHANGES > EDITOR) documents:

Q adds a |multicursor| instead of replaying the last recorded register. To get the old behavior:

vim.keymap.set('n', 'Q', function()
  local reg = vim.fn.reg_recorded()
  return reg == '' and '' or ('@' .. reg)
end, { expr = true })

Under the new EDITOR > NEW FEATURES section, multicursor is also toggled by <C-LeftMouse> and q= (follow mode), cleared with CTRL-L, restored with gQ, and [count]Q places a cursor at every search match.

Where

• Q is not mapped anywhere in this repo (grep -rn '"Q"' across lua/ and init.lua returns nothing), so Nvim's builtin default applies directly — this config gets the new multicursor behavior for free (and loses old-style macro replay) the moment it runs on Nvim 0.13.
• No conflicts with existing keymaps: sneaks.vim (plugin_config.lua) owns f/F/t/T, mini.move uses Alt+hjkl, <leader> is space — Q, q=, CTRL-L, gQ are all free.

Why it matters

Q replaying the last recorded macro (qa...q, then Q to repeat) is long-standing, widely-used vim muscle memory. This is a silent, judgment-call behavior change: some workflows benefit from native multicursor (no plugin needed — mini.nvim doesn't currently provide multicursor and no [idea] issue asks for one), others will be surprised their Q macro-repeat habit stopped working.

This is a genuine nightly-only change (0.13 unreleased, tracked at neovim/neovim#41449) — worth a decision now so it isn't a surprise on upgrade, consistent with how #330 already tracks the sibling :restart behavior change from the same release cycle.

Recommended action

Pick one (both are one-line additions to lua/config/options.lua, near the other single-key remaps like H/L):

1. Keep old Q macro-replay behavior — add the snippet from the news entry above.
2. Embrace native multicursor — no code needed, just be aware Q / q= / CTRL-L / gQ / [count]Q now exist and update the -- usage tips comment block in init.lua (around line 126, next to the existing vim-motion tips) so the behavior isn't a surprise.
3. Do both — remap Q back to macro-replay and pick a different mnemonic for multicursor toggle.

No action needed until upgrading past 0.12.5 to a 0.13 nightly/release.