fix(ci): add -fPIC for static libs and fix Windows find_package verify step

- Set POSITION_INDEPENDENT_CODE ON for all non-INTERFACE targets in dstools_add_library, fixing Linux linker error when static libs are linked into shared libs
- Split Verify find_package(dsfw) CI step into Unix/Windows variants, using shell: cmd on Windows to fix path escaping and MSVC/Ninja availability

Author: wolfgitpr

.github/workflows/build.yml

@@ -257,15 +257,22 @@ jobs:
       - name: Deploy
         run: cmake --build ${{github.workspace}}/build --target install
 
-      - name: Verify find_package(dsfw)
-        shell: bash
+      - name: Verify find_package(dsfw) (Unix)
+        if: runner.os != 'Windows'
         run: |
           cmake -B tests/test-find-package/build -S tests/test-find-package -G Ninja \
             -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} \
             -DCMAKE_PREFIX_PATH="${{github.workspace}}/deploy;${{env.QT_DIR}}/lib/cmake/Qt6/" \
             -DCMAKE_TOOLCHAIN_FILE=${{github.workspace}}/vcpkg/scripts/buildsystems/vcpkg.cmake
           cmake --build tests/test-find-package/build
 
+      - name: Verify find_package(dsfw) (Windows)
+        if: runner.os == 'Windows'
+        shell: cmd
+        run: |
+          cmake -B tests/test-find-package/build -S tests/test-find-package -G Ninja -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DCMAKE_PREFIX_PATH="${{github.workspace}}/deploy;${{env.QT_DIR}}/lib/cmake/Qt6/" -DCMAKE_TOOLCHAIN_FILE="${{github.workspace}}/vcpkg/scripts/buildsystems/vcpkg.cmake"
+          cmake --build tests/test-find-package/build
+
       - name: Set Commit ID
         shell: bash
         run: |

cmake/DstoolsHelpers.cmake

@@ -102,6 +102,9 @@ function(dstools_add_library target_name)
         endif()
 
         add_library(${target_name} ${_type} ${_sources})
+
+        # Ensure static libraries can be linked into shared libraries on Linux
+        set_target_properties(${target_name} PROPERTIES POSITION_INDEPENDENT_CODE ON)
     else()
         add_library(${target_name} INTERFACE)
     endif()