Add EP final roll-call votes of Austrian MEPs

Uses the European Parliament's open data (CC BY 4.0) rather than
HowTheyVote, whose dump is ODbL share-alike and behind a robots.txt block.
Also documents the raw archive ownership step for Unraid.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitattributes

@@ -0,0 +1,2 @@
+# Golden fixtures are compared byte for byte; never convert their line endings.
+backend/tests/fixtures/** -text