refactor(browser-utils): Share MAX_PLAUSIBLE_INP_DURATION between INP handlers

Export the constant from inp.ts and import it in webVitalSpans.ts to
avoid the two definitions drifting apart.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: logaretm

packages/browser-utils/src/metrics/inp.ts

@@ -37,7 +37,7 @@ const ELEMENT_NAME_TIMESTAMP_MAP = new Map<number, string>();
  * 60 seconds is the maximum for a plausible INP value
  * (source: Me)
  */
-const MAX_PLAUSIBLE_INP_DURATION = 60;
+export const MAX_PLAUSIBLE_INP_DURATION = 60;
 /**
  * Start tracking INP webvital events.
  */

packages/browser-utils/src/metrics/webVitalSpans.ts

@@ -20,11 +20,9 @@ import { WINDOW } from '../types';
 import { INP_ENTRY_MAP } from './inp';
 import type { InstrumentationHandlerCallback } from './instrument';
 import { addClsInstrumentationHandler, addInpInstrumentationHandler, addLcpInstrumentationHandler } from './instrument';
+import { MAX_PLAUSIBLE_INP_DURATION } from './inp';
 import { listenForWebVitalReportEvents, msToSec, supportsWebVital } from './utils';
 
-// Maximum plausible INP duration in seconds (matches standalone INP handler)
-const MAX_PLAUSIBLE_INP_DURATION = 60;
-
 interface WebVitalSpanOptions {
   name: string;
   op: string;