feat: add image support for MCP tool responses

[roomote]

Summary

This PR adds support for displaying base64 encoded images returned by MCP tools, fixing the issue where Roo Code couldn't display images from tools like webpage-screenshot-mcp.

Changes

• Updated processToolContent in useMcpToolTool.ts to handle image content types
• Modified the function to return both text and images array
• Added proper base64 data URI construction for images (handles both with and without data URI prefix)
• Updated executeToolAndProcessResult to pass images to both cline.say and pushToolResult
• Added comprehensive tests for single and multiple image handling

Testing

• Added unit tests for image handling in MCP tool responses
• All existing tests continue to pass
• Verified that images are properly formatted as base64 data URIs

Fixes #6163

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Important

Adds support for processing and displaying base64 encoded images in MCP tool responses, with updated tests to verify functionality.

• Behavior:
  • useMcpToolTool in useMcpToolTool.ts now processes base64 encoded images in tool responses, appending them to the result text.
  • Updates processToolContent to extract and format image data, returning both text and image arrays.
  • executeToolAndProcessResult now handles images, sending them with the response.
• Tests:
  • Adds test cases in useMcpToolTool.spec.ts for handling tool responses with single and multiple images.
  • Mocks formatResponse.toolResult to include image count in the result string.
• Misc:
  • Fixes del #6163 by adding image support to MCP tool responses.

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[daniel-lxs]

Related to #5185

[daniel-lxs]

Closing in favor of 5185