Active Storage: Remove dangerous transformations

[CVE-2025-24293]

A subset of transformation methods included in the default allowed list
still present potential command injection risk to applications accepting
arbitrary user input for transformations or their parameters.

Doing so is unsupported behavior and should be considered dangerous.

Author: fresh-eggs

activestorage/lib/active_storage.rb

@@ -74,7 +74,6 @@ module ActiveStorage
     "annotate",
     "antialias",
     "append",
-    "apply",
     "attenuate",
     "authenticate",
     "auto_gamma",
@@ -215,7 +214,6 @@ module ActiveStorage
     "linewidth",
     "liquid_rescale",
     "list",
-    "loader",
     "log",
     "loop",
     "lowlight_color",
@@ -278,7 +276,6 @@ module ActiveStorage
     "rotate",
     "sample",
     "sampling_factor",
-    "saver",
     "scale",
     "scene",
     "screen",

activestorage/test/models/variant_test.rb

@@ -257,7 +257,7 @@ class ActiveStorage::VariantTest < ActiveSupport::TestCase
     process_variants_with :mini_magick do
       blob = create_file_blob(filename: "racecar.jpg")
       assert_raise(ActiveStorage::Transformers::ImageProcessingTransformer::UnsupportedImageProcessingArgument) do
-        blob.variant(saver: { "-write": "/tmp/file.erb" }).processed
+        blob.variant(resize: { "-write": "/tmp/file.erb" }).processed
       end
     end
   end
@@ -266,11 +266,11 @@ class ActiveStorage::VariantTest < ActiveSupport::TestCase
     process_variants_with :mini_magick do
       blob = create_file_blob(filename: "racecar.jpg")
       assert_raise(ActiveStorage::Transformers::ImageProcessingTransformer::UnsupportedImageProcessingArgument) do
-        blob.variant(saver: { "something": { "-write": "/tmp/file.erb" } }).processed
+        blob.variant(resize: { "something": { "-write": "/tmp/file.erb" } }).processed
       end
 
       assert_raise(ActiveStorage::Transformers::ImageProcessingTransformer::UnsupportedImageProcessingArgument) do
-        blob.variant(saver: { "something": ["-write", "/tmp/file.erb"] }).processed
+        blob.variant(resize: { "something": ["-write", "/tmp/file.erb"] }).processed
       end
     end
   end