refactor(growth): remove useTelemetryCookie and sb-telemetry-data cookie

The sb-telemetry-data cookie mechanism is fully superseded by the
_sb_first_referrer edge cookie (GROWTH-625) and the in-memory first-touch
store (GROWTH-656). Remove the hook definition, its export, the
clearTelemetryDataCookie utility, its call in consent.tsx, and the
TELEMETRY_DATA constant.

GROWTH-646

Author: seanoliver

packages/common/constants/local-storage.ts

@@ -111,7 +111,6 @@ export const LOCAL_STORAGE_KEYS = {
    */
   /** @deprecated – we're using usercentrics instead to handle telemetry consent */
   TELEMETRY_CONSENT: 'supabase-consent-ph',
-  TELEMETRY_DATA: 'supabase-telemetry-data',
 
   /**
    * DOCS

packages/common/hooks/index.ts

@@ -13,5 +13,4 @@ export * from './useOnChange'
 export * from './useParams'
 export * from './useSearchParamsShallow'
 export * from './useFirstTouchStore'
-export * from './useTelemetryCookie'
 export * from './useThemeSandbox'

packages/common/hooks/useTelemetryCookie.tsx

@@ -1,4 +1,4 @@
-import { IS_PROD, LOCAL_STORAGE_KEYS } from './constants'
+import { IS_PROD } from './constants'
 import { isBrowser } from './helpers'
 
 export function getTelemetryCookieOptions() {
@@ -10,11 +10,6 @@ export function getTelemetryCookieOptions() {
   return isSupabaseCom ? 'path=/; domain=supabase.com; SameSite=Lax' : 'path=/; SameSite=Lax'
 }
 
-export function clearTelemetryDataCookie() {
-  if (!isBrowser) return
-  document.cookie = `${LOCAL_STORAGE_KEYS.TELEMETRY_DATA}=; expires=Thu, 01 Jan 1970 00:00:00 GMT; max-age=0; ${getTelemetryCookieOptions()}`
-}
-
 // Parse session_id from PostHog cookie since SDK doesn't expose session ID
 // (needed to correlate client and server events)
 function getPostHogSessionId(): string | null {

packages/common/telemetry-utils.ts

@@ -1,6 +1,6 @@
 'use client'
 
-import { clearTelemetryDataCookie, consentState, isBrowser } from 'common'
+import { consentState, isBrowser } from 'common'
 import { useCallback, useEffect, useRef } from 'react'
 import { toast } from 'sonner'
 import { cn } from 'ui'
@@ -26,7 +26,6 @@ export const useConsentToast = () => {
     if (!isBrowser) return
 
     snap.denyAll()
-    clearTelemetryDataCookie()
 
     // Clear GA4 and sGTM tracking cookies
     const trackingCookies = ['_ga', '_ga_XW18KGKGNR', 'FPID', 'FPAU', 'FPLC']