PARIS — Deep fissures in the French Socialist Party that hamstrung the movement during recent municipal elections now threaten to derail its hopes of winning the presidency in 2027. The once-powerful faction is grappling with an identity crisis similar to that gripping left-of-center parties across Europe . But the warring blocs in Paris can’t even agree on the process of choosing a presidential candidate for next year, let alone who should run in a contest that, for now, the far right is