github/runner: use relative paths

Windows expands the build dir with back slash instead of front slash.

Signed-off-by: Ronald Caesar <github43132@proton.me>

.github/workflows/build.yml

@@ -117,7 +117,7 @@ jobs:
           export CCACHE_DIR=${{ runner.os == 'Windows' && '~/AppData/Local/ccache' || '~/.ccache' }}
           export CCACHE_MAXSIZE=500M
           
-          cmake -G Ninja -B ${{ env.BUILD_DIR }} \
+          cmake -G Ninja -B build \
             -DCMAKE_BUILD_TYPE=${{ matrix.type }} \
             -DCMAKE_C_COMPILER="${{ matrix.cc }}" \
             -DCMAKE_CXX_COMPILER="${{ matrix.cxx }}" \
@@ -130,10 +130,11 @@ jobs:
             -DBALLISTIC_ENABLE_LINK_TIME_OPTIMIZATION=${{ matrix.type == 'Release' && 'ON' || 'OFF' }}
 
       - name: Build Project & Docs
-        run: cmake --build ${{ env.BUILD_DIR }} --config ${{ matrix.type }} --target all doc --parallel 4
+        # FIX: Replaced env var with relative path
+        run: cmake --build build --config ${{ matrix.type }} --target all doc --parallel 4
 
       - name: Run Test Suite
-        working-directory: ${{ env.BUILD_DIR }}
+        working-directory: build
         run: ctest -C ${{ matrix.type }} --output-on-failure
 
       - name: Upload Artifacts
@@ -141,8 +142,9 @@ jobs:
         uses: actions/upload-artifact@v4
         with:
           name: ballistic-tools-${{ matrix.os }}
+          # Relative paths are safe in action inputs
           path: |
-            ${{ env.BUILD_DIR }}/ballistic_cli*
-            ${{ env.BUILD_DIR }}/decoder_cli*
-            ${{ env.BUILD_DIR }}/*.exe
+            build/ballistic_cli*
+            build/decoder_cli*
+            build/*.exe
           if-no-files-found: ignore