“The chaos of Donald Trump’s first four months as president has overshadowed a series of actions that could reshape American life for decades — efforts to rewrite or wipe out regulations affecting everything from student loans and restaurant menus to internet privacy, workplace injuries and climate change. Trump and his agencies have already wielded executive actions and Republican control of Congress to postpone, weaken or outright kill dozens of regulations created by Barack Obama’s administration, often using delays in the courtroom to buy time to make those changes. Their targets have included protections for streams from coal-mining pollution and a directive on the rights of transgender students. Other Obama-era regulations are in the crosshairs for possible elimination or downsizing, such as limits on greenhouse gases from power plants and rules meant to prevent concentrated ownership of media companies.