New optional-tier catalog entry, gated on WSL2 detection
(/proc/sys/kernel/osrelease) so it never surfaces on a plain Linux
box's install/sync prompts, only in the informational status
listing. Downloads the x86_64 binary from GitHub releases to
~/.local/bin/win32yank.exe; fish-deps update refreshes an
already-installed copy the same way.
Extracts _fish_clipboard_copy and _fish_clipboard_paste so the
wl-copy/xclip/win32yank fallback chain lives in one place instead of
four near-duplicates. hist now goes through the same chain, so it
also gets the xclip (X11) fallback it was missing before, alongside
win32yank on WSL2.
y, p, paste, and hist now try win32yank.exe after wl-copy/wl-paste
and xclip, so clipboard access works under WSL2 once win32yank is
installed and reachable through WSL interop. Updates the OS
compatibility docs accordingly.
rootiest
