feat: implement comprehensive email system with rate limiting and extensive test suite

- Add robust email service with rate limiting and configuration management
- Implement shared rate limiter utility for consistent API protection
- Create comprehensive test suite for core processing pipeline
- Add API tests for dashboard metrics and authentication routes
- Fix date range picker infinite loop issue
- Improve session lookup in refresh sessions API
- Refactor session API routing with better code organization
- Update processing pipeline status monitoring
- Clean up leftover files and improve code formatting

components/DateRangePicker.tsx

@@ -25,11 +25,7 @@ export default function DateRangePicker({
   useEffect(() => {
     // Only notify parent component when dates change, not when the callback changes
     onDateRangeChange(startDate, endDate);
-  }, [
-    startDate,
-    endDate, // Only notify parent component when dates change, not when the callback changes
-    onDateRangeChange,
-  ]);
+  }, [startDate, endDate]);
 
   const handleStartDateChange = (newStartDate: string) => {
     // Ensure start date is not before min date