Mr. Trump has resisted his itch to fire Fed Chair Jerome Powell on the savvy advice that he could rattle markets and trigger an extended court battle. But Ms. Cook said Tuesday she’ll challenge her removal, so Mr. Trump will still get his legal fight in what could be a landmark case. The Cook firing is a calculated putsch. Federal Housing Finance Agency director Bill Pulte teed up the dismissal last week when he posted a criminal referral for Ms. Cook on social media. He said she may have committed mortgage fraud by claiming two different homes as primary residences...