Update vcpkg cache key in clang-tidy workflow to use specific identifier

Change the cache key prefix from `clang++-19` to `clang-tidy-19` to ensure the vcpkg cache for the clang-tidy job is isolated from standard build caches.

.github/workflows/clang-tidy.yml

@@ -50,7 +50,7 @@ jobs:
         id: vcpkg-cache
         uses: CeetronSolutions/vcpkg-cache@copilot/optimize-cache-storage-structure
         with:
-          cache-key: ${{ runner.os }}-clang++-19-${{ steps.vcpkg-sha.outputs.sha }}-${{ hashFiles('vcpkg.json', 'vcpkg-configuration.json') }}
+          cache-key: ${{ runner.os }}-clang-tidy-19-${{ steps.vcpkg-sha.outputs.sha }}-${{ hashFiles('vcpkg.json', 'vcpkg-configuration.json') }}
 
       - name: Create compile commands and run clang-tidy
         # https://clang.llvm.org/extra/doxygen/run-clang-tidy_8py_source.html