fix: rename VERSION to .version to avoid C++ header conflict

On macOS's case-insensitive filesystem, the VERSION file conflicts with
the C++ standard library header <version> (C++20). When the compiler
tries to #include <version>, it picks up our VERSION file instead,
causing compilation errors.

Solution: Rename VERSION to .version (hidden file with dot prefix)

Updated:
- CMakeLists.txt: Read from .version instead of VERSION
- update_versions.py: Write to .version
- release-please.yml: Upload .version as asset
- release-please-config.json: Track .version in extra-files

This is a known issue on case-insensitive filesystems:
llvm/llvm-project#51214

Author: sameeul

.github/workflows/release-please.yml

@@ -46,12 +46,12 @@ jobs:
           python scripts/update_versions.py --version ${{ steps.release.outputs.version }}
           echo "Updated version files to ${{ steps.release.outputs.version }}"
 
-      - name: Upload VERSION file as release asset
+      - name: Upload .version file as release asset
         if: ${{ steps.release.outputs.release_created }}
         env:
           GH_TOKEN: ${{ github.token }}
         run: |
-          gh release upload ${{ steps.release.outputs.tag_name }} VERSION --clobber
+          gh release upload ${{ steps.release.outputs.tag_name }} .version --clobber
 
   trigger-publish:
     needs: release-please