Add GitHub Copilot instructions for sfmc-devtools

Author: JoernBerkefeld

.github/copilot-instructions.md

@@ -0,0 +1,85 @@
+# GitHub Copilot Instructions for sfmc-devtools
+
+Always assume a bug-ticket might be outdated and first try to verify if the described issue is still occurring.
+
+## Commit Messages
+
+Prefix every commit message with the issue number it was created for:
+
+```
+#1234: <commit message>
+```
+
+Example: `#1234: fix journey deployment error`
+
+## Branch Naming
+
+Branch names must follow this pattern, where the type is derived from the issue type:
+
+```
+copilot/task/1234-issue-title
+copilot/bug/1234-issue-title
+copilot/feature/1234-issue-title
+```
+
+- Use `task` for task/chore issues
+- Use `bug` for bug report issues
+- Use `feature` for feature request/enhancement issues
+- Replace spaces in the issue title with hyphens and use lowercase
+
+## Pull Request Title
+
+The PR title should be derived from the branch name:
+
+```
+Branch: copilot/task/1234-issue-title
+PR title: task/1234 issue title
+```
+
+Format: `<type>/<issue-number> <issue title with spaces>`
+
+## Pull Request Description
+
+Follow the structure defined in [PULL_REQUEST_TEMPLATE.md](./PULL_REQUEST_TEMPLATE.md):
+
+```markdown
+# PR details
+
+## What changes did you make? (Give an overview)
+
+- closes #1234
+
+## Further details (optional)
+
+...
+
+## Checklist
+
+- [ ] I have performed a self-review of my own code
+- [ ] I have commented my code, particularly in hard-to-understand areas
+- [ ] test scripts updated
+- [ ] Wiki updated (if applicable)
+```
+
+Replace `#1234` with the actual issue number the PR is created for.
+
+## Issue Relationship
+
+Always link the PR to the issue it was created for by including `closes #<issue-number>` in the PR description.
+
+## Labels
+
+The repository has component labels prefixed with `c/` based on the class names in `lib/metadataTypes/`. When files in that directory are changed, assign the matching pre-existing `c/` label(s) to the PR.
+
+Examples:
+- Changes to `lib/metadataTypes/Journey.js` → assign label `c/journey`
+- Changes to `lib/metadataTypes/Automation.js` → assign label `c/automation`
+- Changes to `lib/metadataTypes/DataExtension.js` → assign label `c/dataextension`
+
+The label name is `c/` followed by the lower camel-cased class name (filename without extension).
+
+Only assign labels that already exist in the repository.
+
+## Milestone
+
+Assign the same milestone to the PR that the issue has assigned.