remove .gemini/, CONTRIBUTING.md, index.php and phpunit-watcher.yml from composer install

.gitattributes

@@ -1,3 +1,4 @@
+/.gemini export-ignore
 /.github export-ignore
 /tests export-ignore
 /.editorconfig export-ignore
@@ -5,5 +6,8 @@
 /.gitignore export-ignore
 /phpcs.xml export-ignore
 /phpstan.neon export-ignore
+/CONTRIBUTING.md export-ignore
+/index.php export-ignore
 /phpstan-baseline.neon export-ignore
 /phpunit.xml export-ignore
+/phpunit-watcher.yml export-ignore