Change MIME type from `text/html+mcp` to `text/html;profile=mcp-app`
to follow RFC 6838 recommendations for custom media types.
The `+suffix` format (like `text/html+mcp`) is intended for structured
syntax suffixes (e.g., `+json`, `+xml`) that describe the underlying
format. Since MCP Apps doesn't define a new syntax but rather a profile
of HTML, using a profile parameter is more semantically correct.
Fixes#59🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude <noreply@anthropic.com>