docs(desktop): describe how tmux is detected as missing on Windows

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Author: Thewookie-Eng

apps/desktop/README.md

@@ -111,7 +111,7 @@ Build on a Windows host (electron-builder cross-compiles NSIS from macOS/Linux o
 - Signing: set `CSC_LINK`/`CSC_KEY_PASSWORD` to an Authenticode `.pfx`; unsigned builds trigger SmartScreen on first launch.
 - Bun does not run electron's `postinstall` on Windows; if `node_modules/electron/dist/electron.exe` is missing after `bun install`, run `node node_modules/electron/install.js` once.
 
-The agent terminal launches PowerShell (`pwsh`, else Windows PowerShell 5.1) with full shell integration: the hooks are passed as `-EncodedCommand` (a dot-sourced file would be blocked by the default execution policy), `prompt` is wrapped to report the directory, exit code and prompt start, and `PSConsoleHostReadLine` is wrapped to report each command line and its start — the arrangement Windows Terminal and VS Code use. Git for Windows' bash is offered under the app menu's **Terminal Shell** submenu when Git is installed; it uses the existing bash hooks, with `cygpath -w` translating the reported directory to a Windows path. The choice persists as `terminalShell` in `settings.json`. tmux integration is skipped on Windows.
+The agent terminal launches PowerShell (`pwsh`, else Windows PowerShell 5.1) with full shell integration: the hooks are passed as `-EncodedCommand` (a dot-sourced file would be blocked by the default execution policy), `prompt` is wrapped to report the directory, exit code and prompt start, and `PSConsoleHostReadLine` is wrapped to report each command line and its start — the arrangement Windows Terminal and VS Code use. Git for Windows' bash is offered under the app menu's **Terminal Shell** submenu when Git is installed; it uses the existing bash hooks, with `cygpath -w` translating the reported directory to a Windows path. The choice persists as `terminalShell` in `settings.json`. tmux does not exist on Windows; its first probe fails with ENOENT and marks it unavailable for the rest of the session, as on a Mac without tmux.
 
 Windows parity gaps (deliberate, see "Known caveats"): no auto-update (the updater is a no-op off macOS — the installer must be re-downloaded), no Help-menu docs search, no Chrome cookie/password import, and no Terminal.app/iTerm2 theme import.