Update Tooling per current (15Nov2025) picocomputer vscode-cc65

[netzerohero]

1. Add .github subdir; include new file: copilot-instructions.md
2. Remove file: AI_PROMPT.md
3. Update .vscode / settings.json file as: settings.json
4. Update tools/rp6502.cmake as: rp6502.cmake

[netzerohero]

Closed this following PRs #11 and #12 . (Boy am I inefficient in this toolset....).