feat(overtime-contingent) : encart contingent heures supp dans le header fiche employé

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/services/employee-overtime-contingent.ts

@@ -0,0 +1,13 @@
+export interface OvertimeContingent {
+  year: number
+  paidMinutes: number
+  capHours: number
+  isDriver: boolean
+}
+
+export const getEmployeeOvertimeContingent = async (employeeId: number, year?: number) => {
+  const api = useApi()
+  const query: Record<string, number> = {}
+  if (year) query.year = year
+  return api.get<OvertimeContingent>(`/employees/${employeeId}/overtime-contingent`, query, { toast: false })
+}