Fix issue where Chrome extensions specified in the `extensions` field of `config.json` were not being loaded when launching the browser.
## Problem
Extensions configured via the `extensions` field in `config.json` were not being passed to the Chrome browser launch command, causing them to be ignored.
## Changes
- Added `!flags.extensions.is_empty()` to the launch trigger condition to ensure browser launch is triggered when extensions are configured
- Added extensions to the launch command JSON payload so they are properly passed to the browser
Fixes#726