Fix Windows workflow bug and harden CI workflows with --only-binary=:all: (#1493)

Fix bug in Windows workflow where pip install used '.' directory instead
of wheel files, causing setuptools-scm to build from source in shallow
clones and produce invalid fallback versions (0.1.dev...). The bug was
noticed because pathfinder was first built with an invalid version number
due to the shallow clone, and only then replaced with a wheel in a
subsequent step.

Changes:
- Windows: Change 'pip install .' to 'pip install ./*.whl' to prevent source builds
- Linux: Already had the correct pattern, but add --only-binary=:all:
- Both workflows: Systematically add --only-binary=:all: to all pip install
  commands to make intent explicit and guard against accidental source builds

This ensures CI tests the exact artifacts that would be distributed.

Author: rwgk

.github/workflows/test-wheel-linux.yml

@@ -269,17 +269,15 @@ jobs:
       - name: Ensure cuda-python installable
         run: |
           if [[ "${{ matrix.LOCAL_CTK }}" == 1 ]]; then
-            pip install cuda_python*.whl
+            pip install --only-binary=:all: cuda_python*.whl
           else
-            pip install $(ls cuda_python*.whl)[all]
+            pip install --only-binary=:all: $(ls cuda_python*.whl)[all]
           fi
 
       - name: Install cuda.pathfinder extra wheels for testing
         run: |
           set -euo pipefail
           pushd cuda_pathfinder
-          # Install pathfinder from the pre-built wheel, since building from
-          # source won't work in this context (we don't have a git checkout).
           pip install --only-binary=:all: -v ./*.whl --group "test-cu${TEST_CUDA_MAJOR}"
           pip list
           popd

.github/workflows/test-wheel-windows.yml

@@ -236,16 +236,16 @@ jobs:
       - name: Ensure cuda-python installable
         run: |
           if ('${{ matrix.LOCAL_CTK }}' -eq '1') {
-            pip install (Get-ChildItem -Filter cuda_python*.whl).FullName
+            pip install --only-binary=:all: (Get-ChildItem -Filter cuda_python*.whl).FullName
           } else {
-            pip install "$((Get-ChildItem -Filter cuda_python*.whl).FullName)[all]"
+            pip install --only-binary=:all: "$((Get-ChildItem -Filter cuda_python*.whl).FullName)[all]"
           }
 
       - name: Install cuda.pathfinder extra wheels for testing
         shell: bash --noprofile --norc -xeuo pipefail {0}
         run: |
           pushd cuda_pathfinder
-          pip install --only-binary=:all: -v . --group "test-cu${TEST_CUDA_MAJOR}"
+          pip install --only-binary=:all: -v ./*.whl --group "test-cu${TEST_CUDA_MAJOR}"
           pip list
           popd