fix(apm): use dynamic stepInterval for API monitoring time range on endpoints page

Replace hardcoded stepInterval: 300 (5 min) with the computed step value in
all four onViewAPIMonitoringPopupClick calls in External.tsx. Also fix the
endTime formula in util.ts — endTime should be `timestamp` (bucket end), not
`timestamp + stepInterval`, so the destination time range covers exactly the
clicked bar bucket [bucket_start, bucket_end].

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

frontend/src/container/MetricsApplication/Tabs/External.tsx

@@ -263,7 +263,7 @@ function External(): JSX.Element {
 							timestamp: selectedTimeStamp,
 							domainName: selectedData?.address || '',
 							isError: true,
-							stepInterval: 300,
+							stepInterval,
 							safeNavigate,
 						})}
 					/>
@@ -306,7 +306,7 @@ function External(): JSX.Element {
 							timestamp: selectedTimeStamp,
 							domainName: selectedData?.address,
 							isError: false,
-							stepInterval: 300,
+							stepInterval,
 							safeNavigate,
 						})}
 					/>
@@ -352,7 +352,7 @@ function External(): JSX.Element {
 							timestamp: selectedTimeStamp,
 							domainName: selectedData?.address,
 							isError: false,
-							stepInterval: 300,
+							stepInterval,
 							safeNavigate,
 						})}
 					/>
@@ -395,7 +395,7 @@ function External(): JSX.Element {
 							timestamp: selectedTimeStamp,
 							domainName: selectedData?.address,
 							isError: false,
-							stepInterval: 300,
+							stepInterval,
 							safeNavigate,
 						})}
 					/>

frontend/src/container/MetricsApplication/Tabs/util.ts

@@ -151,7 +151,7 @@ export function onViewAPIMonitoringPopupClick({
 	safeNavigate,
 }: OnViewAPIMonitoringPopupClickProps): (e?: React.MouseEvent) => void {
 	return (e?: React.MouseEvent): void => {
-		const endTime = timestamp + (stepInterval || 60);
+		const endTime = timestamp;
 		const startTime = timestamp - (stepInterval || 60);
 		const filters = {
 			items: [