PARIS — Competitors come and go, but Karl Lagerfeld really is the star of the Paris couture. He proved it once again Tuesday morning, with a sharp, focused collection for Chanel that managed to be both chic and hip. Lagerfeld played with the idea of fit-and-flare, using it not only in skirts but in nip-waisted jackets. And he also showed sleek, slightly flared pants. For more on the spring couture, see pages 6 to 8.