Add GitHub Copilot instructions for file reference formatting

[Copilot]

Establishes guidelines for AI assistants to avoid guessing file paths and instead provide searchable file references.

Changes

• Created .github/copilot-instructions.md with three core directives:
  1. Don't guess file paths when uncertain about location
  2. Provide file name and repository context separately
  3. Use repo:user/repo filename syntax for GitHub search compatibility

Example

Instead of providing potentially incorrect paths:

❌ "See /some/assumed/path/to/file.java"

Use searchable references:

✅ "See file.java - use repo:integratedmodelling/klab file.java to locate"
✅ "file.java is in the klab.engine module"

This ensures file references remain valid across repository restructuring and users can reliably locate files via GitHub search.

Original prompt

When providing file links, do not guess the path. Provide the file name and the repository structure separately, or use the repo:user/repo syntax so I can search for it. Apply thies to any future query, please

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