Fix SwiftPM package resolution in GitHub Actions build job

[Copilot]

Description of Changes

The build job was failing during xcodebuild archive with Could not resolve package dependencies on the GitHub Actions runner. This updates the shared CI build helper to pass the Git bare-repository override that SwiftPM now needs during package resolution.

• CI build helper

  • Add a shared safe.bareRepository=all Git config override in scripts/ci/workflow.py
  • Apply it to the xcodebuild/make code paths used for:
    • archive build
    • test build / test run
    • build-settings queries used for metadata generation

• Repo hygiene

  • Ignore Python bytecode/cache artifacts generated while validating the CI helper locally

GIT_CONFIG_COUNT=1 \
GIT_CONFIG_KEY_0=safe.bareRepository \
GIT_CONFIG_VALUE_0=all

Rationale behind Changes

Newer GitHub Actions runner/Git behavior rejects SwiftPM’s use of bare repository caches unless this config is explicitly allowed. Because the failing workflow routes build, test, and metadata operations through scripts/ci/workflow.py, fixing that shared entry point keeps the change small and covers the affected CI paths consistently.

Suggested Testing Steps

• Re-run the previously failing Nightly SideStore Build workflow and confirm the build job gets past package resolution.
• Optionally verify the same path locally by running the CI helper or resolving the Dependencies/SideSign package graph.

Did you use AI to help find, test, or implement this issue or feature?

Yes — AI was used to inspect the failing Actions logs, isolate the package-resolution failure mode, and implement the minimal CI helper change.