Change default involvement for collection access from "watching" to "access_only"

People should opt-in to getting new card notifications

db/migrate/20250912205016_change_default_involvement_to_access_only.rb

@@ -0,0 +1,5 @@
+class ChangeDefaultInvolvementToAccessOnly < ActiveRecord::Migration[8.1]
+  def change
+    change_column_default :accesses, :involvement, "access_only"
+  end
+end