ci: bump SPM cache to v2 to fix stale workspace-state.json pathing override

Author: Aegis-AI

.github/workflows/ci.yml

@@ -30,9 +30,9 @@ jobs:
         uses: actions/cache@v4
         with:
           path: .build
-          key: ${{ runner.os }}-spm-v1-${{ hashFiles('Package.resolved') }}
+          key: ${{ runner.os }}-spm-v2-${{ hashFiles('Package.resolved') }}
           restore-keys: |
-            ${{ runner.os }}-spm-v1-
+            ${{ runner.os }}-spm-v2-
 
       - name: Clear stale module cache
         run: find .build -type d -name ModuleCache -exec rm -rf {} + 2>/dev/null || true