[FEATURE] Support `url` field in `launch.json` for preview feature

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

My dev server runs on https and needs to be accessed via a specific URL. This seems to be incompatible with Claude code's "preview" feature which always connects to localhost

Proposed Solution

Support url in the launch.json configuration that the preview feature reads.

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_