feat(clipboard): add win32yank fallback for 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.

docs/manual/08-components-reference/04-c4-terminal-and-tool-integration.md

@@ -13,7 +13,7 @@ These features couple the shell to specific external tools. Disabling
     spwin                      Kitty or WezTerm
     tab                        Kitty, WezTerm, or Konsole
     split                      Kitty or WezTerm
-    hist                       fzf + wl-copy (Wayland clipboard)
+    hist                       fzf + wl-copy or win32yank.exe (WSL2)
     logs                       fzf + ov; reads from ~/.terminal_history/
     upgrade                    paru or yay (Arch Linux only)
     WakaTime hook              wakatime CLI and a configured API key

docs/manual/10-installation.md

@@ -35,11 +35,14 @@ no fallback:
 - `systemd-inhibit` (`wake-lock`)
 - `zramctl` / `swapon` (`swapstat`)
 - `sbctl` and UEFI Secure Boot state (`sbver`)
-- `wl-copy` / `xclip` for clipboard access (`y`, `p`, `paste`, `hist`) —
-  Wayland or X11 only, no `pbcopy`/`pbpaste` fallback
 - GNU coreutils flags such as `stat -c` and `numfmt` (`sudo-toggle`,
   `dng2avif`), which differ or don't exist under a BSD userland
 
+Clipboard access (`y`, `p`, `paste`, `hist`) is the exception: it falls back
+through `wl-copy`/`wl-paste` (Wayland), `xclip` (X11), and `win32yank.exe`
+(WSL2), so it works on all three. There is still no `pbcopy`/`pbpaste`
+fallback for macOS.
+
 **macOS** is not supported. `_fish_deps_detect_pm` does check for `brew`, but
 that alone does not make the functions above work — they have no macOS
 equivalent path today.
@@ -47,10 +50,10 @@ equivalent path today.
 **Windows** is not supported. Fish itself has no native Windows build;
 upstream's own "Windows" install docs are Cygwin/WSL workarounds, not a real
 port. This config is not tested under WSL either. WSL2 runs a real Linux
-kernel and can run `systemd`, so basic shell use may work, but `zramctl`,
-`sbctl`, and Secure Boot state are meaningless inside a VM, and clipboard
-integration would need a WSL-specific path (`clip.exe`, `win32yank`) that
-does not exist here.
+kernel and can run `systemd`, so basic shell use may work; `zramctl`,
+`sbctl`, and Secure Boot state are still meaningless inside a VM, but
+clipboard integration works via `win32yank.exe` (see above) once it's
+installed on the Windows side and reachable through WSL interop.
 
 **Assumed present on any Linux system this runs on:** `git`, `gpg`, `tar`,
 and GNU coreutils (for `stat`, `date`, `numfmt`). These are not tracked by