fix(multicursor): clipboard=unnamed, explicit "+yy #41804

Problem:
- With `clipboard=unnamed[plus]`, per-cursor yanks are joined into '"'
  on exit, but not the clipboard.
- Multicursor `"+yy` calls the clipboard provider per-cursor, behaving
  as "last wins".

Solution:
- Never cascade to/from the clipboard provider.
- Implicit clipboard (`clipboard=unnamed[plus]`) uses the cursor-local
  unnamed register, so the cascade needs no `start_batch_changes()`. On
  exit, the clipboard gets the same joined result as the `"` register.
- Operations that reference the explicit clipboard registers `"+` / `"*`
  while multicursor is active, use the cached (primary) clipboard value.

0 files changed, 0 insertions, 0 deletions