Add Copilot instructions for repository context

[Copilot]

Configures repository-level instructions to provide GitHub Copilot coding agent with context about the codebase, conventions, and architecture.

Changes

• .github/copilot-instructions.md — Comprehensive guidance covering:
  • AL development environment (Runtime 16.0, BC 27.0, object range 62000-62049)
  • Naming conventions (D4P BC prefix, D4P.CCMS.<FeatureArea> namespaces)
  • Code standards (NoImplicitWith, SecretText for credentials, data classification)
  • AL-Go for GitHub build system configuration
  • Project structure (14 feature areas under src/)
  • Security patterns and design principles
  • Common workflows and governance model references

Enables Copilot to generate code consistent with Business Central AL conventions and CCMS architectural patterns.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• gh.io
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ✨ Set up Copilot instructions #4

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.