fix: align explorer source manifest

Normalize the pre-existing trailing blank line so all 11 Space files are byte-identical to the reviewed GitHub source at merge ffe580ecca7bbf2788d677ef45e4f52a71cdbc8d.

src/h2epr_explorer/__init__.py

@@ -1,2 +1 @@
 """Support modules for the H2EPR-Bench Explorer Space."""
-