Adds automatic trace propagation from server to client via the Server-Timing HTTP header for Remix applications.

This provides an alternative to meta tag injection for linking server and client traces. The server automatically injects sentry-trace and baggage into the Server-Timing response header, and the client SDK reads it via the Performance API during pageload.

Server-side:

• generateSentryServerTimingHeader() - generates the header value
• addSentryServerTimingHeader(response) - adds header to a Response
• Automatic injection in document request handler
• Cloudflare apps require manual response wrapping in entry.server.tsx using addSentryServerTimingHeader

Client-side:

• Reads Server-Timing from navigation timing entries
• Falls back to meta tags if Server-Timing unavailable
• Async retry mechanism for slow header processing

Works on both Node.js and Cloudflare Workers environments.