fix: re-inject user data when widget signals it is ready

[alperbilgic]

Problem

User data (name, email, identifier), locale, custom attributes, and color scheme are intermittently not applied to the Chatwoot widget. This is a race condition reported in #31.

Root cause

injectedJavaScript fires as soon as the WebView page finishes loading, but the Chatwoot widget's internal JavaScript may not have initialized its message event listeners at that point. The window.postMessage() calls containing user data are silently dropped.

Solution

Add a WebView ref and re-inject the user/locale/customAttributes/colorScheme scripts when the widget fires its loaded event — the exact moment it signals readiness to receive messages.

• The existing injectedJavaScript prop is kept as an optimistic first attempt (works when timing is favorable)
• The loaded event handler acts as a reliable, event-driven fallback

This is a minimal, non-breaking change — only src/WebView.js is touched.

Changes

1. Import useRef from React
2. Create a webViewRef and attach it to the <WebView> component
3. In the onMessage handler, when eventType === 'loaded', call webViewRef.current.injectJavaScript() with the same scripts

Related issues

Fixes #31