Add Homebridge Config UI (homebridge-ui) and split device config into on_off/stateless sections

[pponce]

Motivation

• Provide a richer, user-friendly Homebridge Config UI X experience for Script2 by adding a custom UI and grouping device configuration into explicit on_off_switches and stateless_switches sections.
• Preserve backward compatibility by keeping a legacy devices array and migrating support so existing installs do not break.

Description

• Add a custom UI under homebridge-ui including public/index.html, public/index.js and a small UI server server.js that uses HomebridgePluginUiServer to serve the plugin configuration UI.
• Update config.schema.json to enable customUi/customUiPath, introduce on_off_switches and stateless_switches arrays with full schema fields and validation, and keep a conditional legacy devices array for backward compatibility.
• Update README.md to document the new UI-driven sections and migration notes, and add an Installation section and examples for both new grouped config and legacy devices config.
• Bump package version and add the @homebridge/plugin-ui-utils dependency in package.json required by the UI server.

Testing

• No automated tests were run for this change.

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Codex Task