refactor: delete dead ScreenshotAssertion.from method

No production callers remain after replacing tuple protocol with
direct construction. Update 2 tests to construct directly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pftg

lib/capybara_screenshot_diff/screenshot_assertion.rb

@@ -14,16 +14,6 @@ def initialize(name, **args, &block)
       yield(self) if block_given?
     end
 
-    def self.from(screenshot_job)
-      return screenshot_job if screenshot_job.is_a?(ScreenshotAssertion)
-
-      caller, name, compare = screenshot_job
-      ScreenshotAssertion.new(name).tap do |assertion|
-        assertion.caller = caller
-        assertion.compare = compare
-      end
-    end
-
     def validate
       return unless compare
 

test/unit/diff_test.rb

@@ -155,7 +155,9 @@ def _test_sample_screenshot_error
           mock.expect(:base_image_path, Pathname.new("screenshot.base.png"))
           mock.expect(:error_message, "expected error message")
 
-          assertion = CapybaraScreenshotDiff::ScreenshotAssertion.from([["my_test.rb:42"], "sample_screenshot", mock])
+          assertion = CapybaraScreenshotDiff::ScreenshotAssertion.new("sample_screenshot")
+          assertion.caller = ["my_test.rb:42"]
+          assertion.compare = mock
           CapybaraScreenshotDiff.add_assertion(assertion)
 
           assert true
@@ -189,7 +191,9 @@ def _test_sample_screenshot_error
           comparison.expect(:base_image_path, Pathname.new("screenshot.base.png"))
           comparison.expect(:error_message, "expected error message for non minitest")
 
-          assertion = CapybaraScreenshotDiff::ScreenshotAssertion.from([["my_test.rb:42"], "sample_screenshot", comparison])
+          assertion = CapybaraScreenshotDiff::ScreenshotAssertion.new("sample_screenshot")
+          assertion.caller = ["my_test.rb:42"]
+          assertion.compare = comparison
           CapybaraScreenshotDiff.add_assertion(assertion)
         end
       end