[Copilot]

What

• Move the ArcGIS Pro add-in build into GitHub Actions instead of relying on a manually refreshed checked-in artifact.
• Workflow changes
  • Add a build_addin job to CI and release workflows on self-hosted, windows, arcgispro.
  • Resolve MSBuild.exe via vswhere, build ProExporter.sln, and publish the generated .esriAddinX as ProExporter.addin.
  • Make the package build jobs download that artifact and place it at cli/arcgispro_cli/addin/ProExporter.addin before python -m build.
• Security
  • Set workflow-level contents: read permissions and preserve the release publish job’s explicit OIDC permission.
• Docs
  • Update the development docs to reflect that CI now rebuilds the bundled add-in; local Visual Studio builds remain for local add-in work.

build_addin:
  runs-on: [self-hosted, windows, arcgispro]

Why

• The packaged CLI includes a bundled add-in, but CI previously only verified packaging of whatever artifact was already in the repo.
• Building the add-in in CI removes the manual pre-commit refresh step and ensures package outputs are produced from a freshly built add-in.

How to test

• On a self-hosted Windows runner labeled arcgispro, run the CI workflow and confirm:
  • build_addin produces ProExporter.addin
  • the package build downloads that artifact before python -m build
  • the built wheel contains arcgispro_cli/addin/ProExporter.addin
• Trigger the release workflow and confirm it follows the same artifact handoff path.

Notes / risks

• This depends on a self-hosted Windows runner with ArcGIS Pro, the Pro SDK, and MSBuild available.
• If that runner is unavailable or mislabeled, CI/release packaging will block rather than silently package a stale add-in.

• Fixes Add addin build as a CI step instead of doing it manually before each commit #49