feat: add Claude plugin browser URL config

[officialasishkumar]

Summary

• add a Claude plugin browserUrl user config option for connecting to a running debuggable Chrome instance
• pass the option through to chrome-devtools-mcp with --browser-url, while a blank value keeps the default automatic Chrome launch behavior
• document the Claude Code pluginConfigs settings shape for the plugin option

Fixes #1232

Testing

• parsed .claude-plugin/plugin.json with JSON.parse
• npm run check-format
• npm run gen

[OrKoN]

Thanks for the PR, we should implement the suggestion from #1981 (comment) to generate all configuration options.

[OrKoN]

We should update the generator to generate the userConfig options as suggested in #1981 (comment)

[officialasishkumar]

Updated this to generate plugin userConfig from the CLI options and wire the generated values through env defaults, so browserUrl and future options are not maintained by hand.

[OrKoN]

I think we should keep using arguments for the configuration and do not introduce environment variables. I think the initial version of this PR used arguments.

[OrKoN]

I think I actually saw this in another PR #1981

[officialasishkumar]

Updated this in 8b3a6e2: generated plugin user config now stays on CLI args, and the env-default path was removed.