Problem: resolving the last conflict called M.detach(), which cleared
attached_buffers[bufnr]. The TextChanged callback then returned true,
permanently deleting the autocmd. Undo restored conflict markers but
nothing re-highlighted or re-suppressed diagnostics.
Solution: inline the cleanup in refresh() instead of calling detach().
Keep attached_buffers set so the autocmd survives. Re-suppress
diagnostics when conflicts reappear after undo.
Problem: when git hits a merge conflict, users stare at raw <<<<<<<
markers with broken treesitter and noisy LSP diagnostics. Existing
solutions (git-conflict.nvim) use their own highlighting rather than
integrating with diffs.nvim's color blending pipeline.
Solution: add conflict.lua module that detects <<<<<<</=======/>>>>>>>
markers (with diff3 ||||||| support), highlights ours/theirs/base
regions with blended DiffsConflict* highlight groups, provides
resolution keymaps (doo/dot/dob/don) and navigation (]x/[x),
suppresses diagnostics while markers are present, and auto-detaches
when all conflicts are resolved. Fires DiffsConflictResolved user
event on last resolution.
