Its definitely awesome that your cat is scratching, and good you want to keep their claws trimmed. Sharp claws can get caught in fabrics, and hurt other pets.
Bad news! Scratching actually sharpens their claws and pulls the old nail sheaths off the new razor sharp claw beneath.
Good news! You can trim your cat's claws for the price of a pair of clippers.
Just be patient and gentle and calm and they'll get used to it. My formerly feral rescue cats sleep through it now after years of it. The first few times, I'd just clip as many as they'd calmly let me. Now the clippers are like the brush, and they purr.