fix: add missing cwd to runScript spawn

[Hugo-DL]

Fixes #5

Problem

npx openutter join fails with ERR_MODULE_NOT_FOUND: Cannot find package 'tsx' when run from any directory that does not have tsx in its node_modules.

Root Cause

runScript() spawns Node with --import tsx but does not set cwd: pkgRoot. Node resolves tsx relative to the current working directory instead of the package root where tsx is actually installed.

Fix

One-line change: add cwd: pkgRoot to the spawnSync options in runScript(), consistent with runNodeCommand() and runPlaywrightCommand() which already set this.

Testing

Before fix:

cd /tmp && npx openutter join https://meet.google.com/abc --anon --bot-name "Bot"
# → ERR_MODULE_NOT_FOUND: Cannot find package 'tsx'

After fix:

cd /tmp && npx openutter join https://meet.google.com/abc --anon --bot-name "Bot"
# → Works correctly (tsx resolved from package node_modules)