Update MIME types for UI resources to include profile for MCP Apps

[mattdholloway]

Summary

Updates MCP Apps MIME types to include the correct profile

Why

For parity with the TypeScript SDK examples

What changed

MIME type updates for UI resources:

• Changed the MIMEType for the "get_me_ui" resource and its response contents from "text/html" to "text/html;profile=mcp-app" to specify the MCP App profile.
• Updated the MIMEType for the "issue_write_ui" resource and its response contents to "text/html;profile=mcp-app".
• Set the MIMEType for the "pr_write_ui" resource and its response contents to "text/html;profile=mcp-app".

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

Prompts tested (tool changes only)

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

• Linted locally with ./script/lint
• Tested locally with ./script/test

Docs

• Not needed
• Updated (README / docs / examples)

[Copilot]

Pull request overview

Updates the registered UI resource MIME types so MCP Apps clients can identify them via the profile=mcp-app media type parameter.

Changes:

• Updated mcp.Resource MIME types for embedded UI resources to text/html;profile=mcp-app.
• Updated the corresponding mcp.ResourceContents MIME types to match.