Update lab docs and images for latest Copilot features

- Added and updated images to illustrate new Copilot UI and features
- Revised walkthroughs for clarity and alignment with current Copilot and VS experience
- Added instructions for enabling Ask mode, completions, and Next Edit Suggestions, with supporting screenshots
- Updated model references to "Claude 4.5 Sonnet"
- Improved inline chat instructions and prompt examples
- Standardized navigation links and checklist formatting
- Clarified copilot-instructions.md location and added new tips throughout

Update lab docs and assets for VS2026 & Copilot enhancements

Significantly revised lab documentation and images to reflect Visual Studio 2026 and the latest GitHub Copilot features. Added new screenshots for Ask mode, Planning mode, MCP server setup, and cloud delegation. Updated instructions for enabling Copilot features, using MCP servers, and leveraging new agent and planning workflows. Added .mcp.json to the solution and updated the solution file accordingly. Improved clarity, navigation, and step-by-step guidance throughout the lab to align with the current Copilot Chat experience.

Author: jamesmontemagno