fix(fileio): do not remove destination file before rename (#42152)

* fix(fileio): do not remove destination file before rename

Problem:
`vim_rename()` unconditionally removes the destination file `to` via
`os_remove(to)` before calling `os_rename(from, to)`.
If Neovim is killed or a crash occurs between `os_remove()` and
`os_rename()`, the destination file is lost. For example, during
`shada_write_file()`, `main.shada` is deleted before being replaced by
`main.shada.tmp.a`, which can lead to silent loss of command history,
marks, and registers. Furthermore, if `os_rename()` subsequently fails,
the destination was already destroyed.

Solution:
In Neovim, `os_rename()` uses `uv_fs_rename()`, which atomically replaces
existing destination files on both POSIX (`rename(2)`) and Windows
(`MoveFileExW(..., MOVEFILE_REPLACE_EXISTING)`).
Attempt `os_rename(from, to)` first. Only if it fails (e.g. cross-device
link) and copying is required as a fallback, remove `to` before
`vim_copyfile()`.

Fixes #41940

AI-assisted

* fix(fileio): retry rename after removing destination

Retry the native rename after successfully removing the destination so a
directory can still replace an existing file. Keep the initial rename
attempt before removal and the existing copy fallback.

AI-assisted

0 files changed, 0 insertions, 0 deletions