The ornate Belle Epoque theatre had lost its luster, visually and artistically, by the end of the last century. But the house’s director, Olivier Mantei, is determined to bring excitement and audiences back. So he’s overseen a meticulous restoration of the building to its original splendor, reopened it with a spectacular revival of a grand opera not seen in Paris for 246 years, and even commissioned a patisserie to create a new cake for the occasion.