Allow missing Scripts directory (#16206)

With the new Python install manager, the `Scripts` directory reported by
Python may not exist.

See https://github.com/astral-sh/uv/pull/16205 for a failing CI run:
https://github.com/astral-sh/uv/actions/runs/18377230241/job/52354460636?pr=16205#step:4:15

Fixes https://github.com/astral-sh/uv/issues/16204

.github/workflows/ci.yml

@@ -1289,6 +1289,30 @@ jobs:
           ./uv run python -c ""
           ./uv run -p 3.13 python -c ""
 
+  integration-test-windows-python-install-manager:
+    timeout-minutes: 10
+    needs: build-binary-windows-x86_64
+    name: "integration test | windows python install manager"
+    runs-on: windows-latest
+
+    steps:
+      - name: "Download binary"
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+        with:
+          name: uv-windows-x86_64-${{ github.sha }}
+
+      - name: "Install Python via Python Install manager"
+        run: |
+          # https://www.python.org/downloads/release/pymanager-250/
+          winget install --accept-package-agreements --accept-source-agreements 9NQ7512CXL7T
+          # Call Python Install Manager's py.exe by full path to avoid legacy py.exe
+          & "$env:LOCALAPPDATA\Microsoft\WindowsApps\py.exe" install 3.14
+
+      # https://github.com/astral-sh/uv/issues/16204
+      - name: "Check temporary environment creation"
+        run: |
+          ./uv run -p $env:LOCALAPPDATA\Python\pythoncore-3.14-64\python.exe --with numpy python -c "import sys; print(sys.executable)"
+
   integration-test-pypy-linux:
     timeout-minutes: 10
     needs: build-binary-linux-libc