Add duty cycle display to repeaters. Closes #308.

frontend/src/test/repeaterDashboard.test.tsx

@@ -499,6 +499,7 @@ describe('RepeaterDashboard', () => {
       radio: '910.5250244,62.5,7,5',
       tx_power: '20',
       airtime_factor: '0',
+      duty_cycle_limit: '100.0%',
       repeat_enabled: '1',
       flood_max: '3',
     };

frontend/src/test/useRepeaterDashboard.test.ts

@@ -336,6 +336,7 @@ describe('useRepeaterDashboard', () => {
       radio: null,
       tx_power: null,
       airtime_factor: null,
+      duty_cycle_limit: null,
       repeat_enabled: null,
       flood_max: null,
     });