Track language selection with Plausible Language Changed event.

Centralize UI language switches in cycleAppLanguage and document the event in plausible-events.md.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/components/AuthOnboarding.tsx

@@ -1,6 +1,6 @@
 import React, { useState } from 'react'
 import { useTranslation } from 'react-i18next'
-import { getNextLanguage } from '../utils/i18nLanguages.js'
+import { cycleAppLanguage, getNextLanguage } from '../utils/i18nLanguages.js'
 import { 
   registerUser, 
   loginUser, 
@@ -210,7 +210,7 @@ export default function AuthOnboarding({ onAuthenticated, onOpenDemo }: AuthOnbo
   }
 
   const toggleLanguage = () => {
-    i18n.changeLanguage(getNextLanguage(i18n.language))
+    cycleAppLanguage(i18n)
   }
 
   const copyToClipboard = () => {

client/src/components/DemoViewer.tsx

@@ -1,6 +1,6 @@
 import { useState, useEffect } from 'react'
 import { useTranslation } from 'react-i18next'
-import { getNextLanguage } from '../utils/i18nLanguages.js'
+import { cycleAppLanguage, getNextLanguage } from '../utils/i18nLanguages.js'
 import VesselForm from './VesselForm.tsx'
 import CrewForm from './CrewForm.tsx'
 import LogEntriesList from './LogEntriesList.tsx'
@@ -49,7 +49,7 @@ export default function DemoViewer({ onExit }: DemoViewerProps) {
   }, [registerNavigation, registerDemoTourContext, startTour, fixture.firstEntryId])
 
   const toggleLanguage = () => {
-    i18n.changeLanguage(getNextLanguage(i18n.language))
+    cycleAppLanguage(i18n)
   }
 
   const { title, yacht, crews, entries, gpsTracks, photos, firstEntryId } = fixture

client/src/components/InvitationAcceptance.tsx

@@ -1,6 +1,6 @@
 import React, { useState, useEffect, useCallback, useRef } from 'react'
 import { useTranslation } from 'react-i18next'
-import { getNextLanguage } from '../utils/i18nLanguages.js'
+import { cycleAppLanguage, getNextLanguage } from '../utils/i18nLanguages.js'
 import { Ship, LogIn, UserPlus, AlertTriangle, ShieldCheck, Languages, ArrowRight, KeyRound } from 'lucide-react'
 import {
   getActiveMasterKey,
@@ -309,7 +309,7 @@ export default function InvitationAcceptance({ onAccepted, onCancel }: Invitatio
   }
 
   const toggleLanguage = () => {
-    i18n.changeLanguage(getNextLanguage(i18n.language))
+    cycleAppLanguage(i18n)
   }
 
   if (recoveryPhrase) {

client/src/components/LogbookDashboard.tsx

@@ -1,6 +1,6 @@
 import React, { useState, useEffect, useRef, useMemo } from 'react'
 import { useTranslation } from 'react-i18next'
-import { getNextLanguage } from '../utils/i18nLanguages.js'
+import { cycleAppLanguage } from '../utils/i18nLanguages.js'
 import { useSyncIndicator } from '../hooks/useSyncIndicator.js'
 import { fetchLogbooks, createLogbook, deleteLogbook, updateLogbookTitle, type DecryptedLogbook } from '../services/logbook.js'
 import LogbookRoleBadge from './LogbookRoleBadge.tsx'
@@ -194,7 +194,7 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
   }
 
   const toggleLanguage = () => {
-    i18n.changeLanguage(getNextLanguage(i18n.language))
+    cycleAppLanguage(i18n)
   }
 
   const ownedLogbooks = logbooks.filter((lb) => !lb.isShared)

client/src/components/ReadOnlyViewer.tsx

@@ -1,6 +1,6 @@
 import { useState, useEffect } from 'react'
 import { useTranslation } from 'react-i18next'
-import { getNextLanguage, isGermanLocale } from '../utils/i18nLanguages.js'
+import { cycleAppLanguage, getNextLanguage, isGermanLocale } from '../utils/i18nLanguages.js'
 import { decryptJson } from '../services/crypto.js'
 import { PlausibleEvents, trackPlausibleEvent } from '../services/analytics.js'
 import VesselForm from './VesselForm.tsx'
@@ -137,7 +137,7 @@ export default function ReadOnlyViewer({ token, hexKey }: ReadOnlyViewerProps) {
   }
 
   const toggleLanguage = () => {
-    i18n.changeLanguage(getNextLanguage(i18n.language))
+    cycleAppLanguage(i18n)
   }
 
   if (loading) {