Update class mechanics, stat rulesets, and CoA reference catalogs

.gitignore

@@ -23,3 +23,9 @@ dist-android/
 .web-public/
 __pycache__/
 *.pyc
+
+# Local CoA reference downloads and immutable generated snapshots.
+/data/coa-reference/cache/
+/data/coa-reference/snapshots/
+/data/coa-reference/current.json
+/data/coa-reference/.current-*.tmp