🧪 Add tests for split_repo and restore Python 3.14 workflow setup

tests/scripts/ci/test_pr_review_merge_scheduler.py

@@ -0,0 +1,19 @@
+import pytest
+from scripts.ci.pr_review_merge_scheduler import split_repo
+
+def test_split_repo_valid():
+    assert split_repo("owner/name") == ("owner", "name")
+    assert split_repo("owner/name/extra") == ("owner", "name/extra")
+
+def test_split_repo_invalid():
+    with pytest.raises(ValueError, match="repo must be owner/name, got 'owner'"):
+        split_repo("owner")
+
+    with pytest.raises(ValueError, match="repo must be owner/name, got '/name'"):
+        split_repo("/name")
+
+    with pytest.raises(ValueError, match="repo must be owner/name, got 'owner/'"):
+        split_repo("owner/")
+
+    with pytest.raises(ValueError, match="repo must be owner/name, got '/'"):
+        split_repo("/")