fix(windows): pass explicit working directory to ttyd to prevent Error 267

[gitKashish]

Fixes #754.

This PR fixes a bug where vhs panics and crashes during setup on Windows when using the latest official ttyd release (v1.7.7). I encountered this exact issue when running powershell tapes.

The Bug
When running a tape file on Windows, vhs panics because the ttyd server instantly crashes in the background, causing go-rod to lose its WebSocket connection:

$ vhs .\v3-release.tape
File: .\v3-release.tape
Output .gif demo.gif
Set FontSize 46
Set Width 1200
Set Height 600

panic: write tcp 127.0.0.1:54658->127.0.0.1:54656: use of closed network connection
goroutine 1 [running]:
github.com/go-rod/rod/lib/utils.init.func2({0x7ff668433060?, 0x3b03f87e320?})
        /home/runner/go/pkg/mod/github.com/go-rod/rod@v0.116.2/lib/utils/utils.go:68 +0x1d
...

The Investigation
Running the vhs background command (ttyd -p 7654 powershell) manually reveals that ttyd is crashing natively with:
== CreateProcessW failed with error 267: The directory name is invalid.

This is a known issue in ttyd (see tsl0922/ttyd#1292). In the Windows source code (pty_spawn), if a working directory isn't explicitly provided, the default directory resolution fails and passes a malformed string to CreateProcessW (see the exact lines throwing the error.

Upstream Context & Fix
This directory resolution bug seems to have been addressed upstream in ttyd PR tsl0922/ttyd#1502. However, ttyd has not cut a new release in over 2 years, meaning all vhs Windows users downloading the latest official binaries are still subjected to this crash.

By explicitly appending -w . to the ttyd arguments inside tty.go for Windows, we force ttyd to use the current native directory. This bypasses the upstream bug entirely and allows vhs to successfully spawn the process and record the tape.

Steps to Reproduce (Before)

1. Ensure you have the latest release binary of ttyd (1.7.7) on Windows.
2. Run vhs demo.tape.
3. vhs panics with use of closed network connection.

Steps to Reproduce (After)

1. Run vhs demo.tape on Windows.
2. ttyd successfully launches the shell using the explicit -w . flag.
3. The tape finishes recording and successfully outputs the GIF.