Fix uv fallback in the shared runtime setup

[Copilot]

The Code Complexity Detector workflow was failing before the agent actually started because the shared runtime setup assumed setup-uv always exposed a usable uv-path. In practice, that output can be empty, causing the workflow to fail during the Expose uv in workspace step.

• Root cause

  • The shared runtime setup fragment in .github/workflows/gh-aw-fragments/runtime-setup.md hard-linked the uv symlink to ${{ steps.setup-uv.outputs.uv-path }}.
  • When that output is missing or blank, the step exits early and the agent never begins.

• Fix

  • Added a defensive fallback to the active uv binary discovered via command -v uv when UV_PATH is unset.
  • Kept the failure explicit and actionable if uv is truly absent, instead of failing silently with a broken symlink path.
  • Regenerated the compiled Code Complexity Detector workflow so the fix is reflected in the lock file used by the workflow run.

uv_bin="${UV_PATH:-$(command -v uv || true)}"
if [ -z "$uv_bin" ]; then
  echo "::error::uv was not installed or not discoverable after setup-uv" >&2
  exit 1
fi
sudo ln -sf "$uv_bin" "$toolcache_bin/uv"

• Impact

  • The workflow now survives the setup-uv edge case and continues into the agent runtime instead of dying during environment setup.
  • The fix is centralized in the shared fragment, so all workflows that rely on the same uv exposure pattern inherit the safeguard.

• Fixes [aw] Failed jobs: Code Complexity Detector #2004