Avoid installed app handoff screen

src/App.vue

@@ -369,14 +369,12 @@ const canContinue = computed(() => {
   return true
 })
 const pwaInstallTitle = computed(() => {
-  if (pwaInstallMessage.value) return 'Open the L484 app'
   if (isPwaStandalone.value) return 'PWA installed'
   if (installPlatform.value === 'ios') return 'Install L484 on iPhone'
   if (installPlatform.value === 'android') return 'Install L484 on Android'
   return 'Install L484 on this device'
 })
 const pwaInstallCopy = computed(() => {
-  if (pwaInstallMessage.value) return 'Continue signup in the installed app. It will start at name entry.'
   if (installPlatform.value === 'ios') return 'Use Safari, tap Share, then Add to Home Screen. Reopen L484 from the new app icon to continue signup.'
   return 'Press Install app to open the browser install prompt.'
 })
@@ -787,10 +785,9 @@ const handleBeforeInstallPrompt = (event) => {
 
 const handlePwaInstalled = () => {
   deferredInstallPrompt.value = null
-  signupStep.value = 1
   saveSignupDraft(2)
-  pwaInstallMessage.value = 'Installed. Open L484 from your homescreen to continue.'
   refreshPwaStandalone()
+  openInstalledApp()
 }
 
 const handlePwaInstallPrimary = async () => {
@@ -809,9 +806,8 @@ const handlePwaInstallPrimary = async () => {
     await promptEvent.prompt()
     const choice = await promptEvent.userChoice.catch(() => null)
     if (choice?.outcome === 'accepted') {
-      signupStep.value = 1
       saveSignupDraft(2)
-      pwaInstallMessage.value = 'Installed. Open L484 from your homescreen to continue.'
+      openInstalledApp()
       return
     }
     formError.value = 'Install L484 before continuing signup.'
@@ -819,9 +815,8 @@ const handlePwaInstallPrimary = async () => {
   }
 
   if (installPlatform.value === 'desktop' || installPlatform.value === 'android') {
-    signupStep.value = 1
     saveSignupDraft(2)
-    pwaInstallMessage.value = 'L484 may already be installed on this device. Open the installed app to finish signup.'
+    openInstalledApp()
     return
   }
 
@@ -829,9 +824,18 @@ const handlePwaInstallPrimary = async () => {
 }
 
 const openInstalledApp = () => {
-  signupStep.value = 2
-  saveSignupDraft()
-  window.location.href = '/?signup=continue'
+  saveSignupDraft(2)
+  let didLeave = false
+  const fallback = window.setTimeout(() => {
+    if (didLeave) return
+    signupStep.value = 2
+  }, 900)
+  const markLeave = () => {
+    didLeave = true
+    window.clearTimeout(fallback)
+  }
+  window.addEventListener('pagehide', markLeave, { once: true })
+  window.location.href = 'web+l484://signup'
 }
 
 const startSignup = async () => {
@@ -3508,9 +3512,6 @@ watch(mobileMenuOpen, (open) => {
             <p v-if="pwaInstallMessage" class="validation-message rounded border border-white/15 bg-white/5 p-3 text-sm text-white/70">
               Open the L484 app icon on your homescreen. Signup will continue at name entry.
             </p>
-            <button v-if="pwaInstallMessage" class="primary-action w-full" type="button" @click="openInstalledApp">
-              Open app
-            </button>
           </div>
 
           <div v-if="signupStep === 2" class="space-y-4">