Pfizer agreed to buy obesity-drug developer Metsera for about $10 billion, topping a rival offer from Novo Nordisk and resolving a public bidding fight. The proposal offers up to $86.25 per share in cash and was accepted by Metsera late Friday, ending litigation and uncertainty that had roiled both bidders. The transaction secures Metsera’s next-generation obesity portfolio for Pfizer and removes a key asset from an intensifying market for weight-loss therapies.