Freeze independently reviewed relevance calibration corpus

fixtures/relevance-v2/.gitattributes

@@ -0,0 +1,5 @@
+sources/** -text
+licenses/** -text
+# Frozen hashes cover JSON and review history as exact bytes, too.
+*.json -text whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol
+review-history/** -text whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol