Menu: add "Back to Landing Page" (stay signed in) alongside Logout

The landing page is the dispatch hub for the other LUSPA modules. Add a plain
navigation link to https://lupmis4luspa.org/ that keeps the SSO session intact
(no /?logout=1, no cache wipe), shown only when authenticated. Logout remains
the full SSO sign-out via /user-logout.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

dist/index.html

@@ -1601,7 +1601,7 @@
       }
     }
   </style>
-  <script type="module" crossorigin src="/assets/index-Ko1mW_fQ.js"></script>
+  <script type="module" crossorigin src="/assets/index-DfnW4iL8.js"></script>
   <link rel="modulepreload" crossorigin href="/assets/openlayers-D8ReJJOp.js">
   <link rel="modulepreload" crossorigin href="/assets/bootstrap-D1-uvFxm.js">
   <link rel="modulepreload" crossorigin href="/assets/ol-ext-P1ircg-B.js">
@@ -2060,9 +2060,21 @@
 
       <hr>
 
+      <!-- Back to Landing Page (stay signed in) — visible when authenticated.
+           The landing page is the dispatch hub for launching the other LUSPA
+           modules. Plain navigation: keeps the SSO session, no logout. -->
+      <a id="menu-landing-link"
+         href="https://lupmis4luspa.org/"
+         class="btn btn-primary w-100 d-none mb-2"
+         style="font-weight:600;">
+        <i class="bi bi-grid-3x3-gap-fill me-2"></i>Back to Landing Page
+      </a>
+
       <!-- Logout (only visible when authenticated) — routes through the
-           server logout endpoint (/?logout=1) so the PWA's own PHP session
+           server logout endpoint (/?logout=1) which destroys the PWA's PHP
-           is destroyed, not just the SSO cookie. -->
+           session and hands off to the portal's /user-logout for full SSO
+           logout. Distinct from "Back to Landing Page" above, which stays
+           signed in. -->
       <button type="button" id="menu-signout-btn"
               class="btn btn-outline-danger w-100 d-none"
               style="font-weight:600;">

index.html

@@ -2051,9 +2051,21 @@
 
       <hr>
 
+      <!-- Back to Landing Page (stay signed in) — visible when authenticated.
+           The landing page is the dispatch hub for launching the other LUSPA
+           modules. Plain navigation: keeps the SSO session, no logout. -->
+      <a id="menu-landing-link"
+         href="https://lupmis4luspa.org/"
+         class="btn btn-primary w-100 d-none mb-2"
+         style="font-weight:600;">
+        <i class="bi bi-grid-3x3-gap-fill me-2"></i>Back to Landing Page
+      </a>
+
       <!-- Logout (only visible when authenticated) — routes through the
-           server logout endpoint (/?logout=1) so the PWA's own PHP session
+           server logout endpoint (/?logout=1) which destroys the PWA's PHP
-           is destroyed, not just the SSO cookie. -->
+           session and hands off to the portal's /user-logout for full SSO
+           logout. Distinct from "Back to Landing Page" above, which stays
+           signed in. -->
       <button type="button" id="menu-signout-btn"
               class="btn btn-outline-danger w-100 d-none"
               style="font-weight:600;">

main.js

@@ -3927,6 +3927,7 @@ function initAccountCard() {
   const emailEl    = document.getElementById('menu-user-email');
   const detailEl   = document.getElementById('menu-user-detail');
   const signoutBtn = document.getElementById('menu-signout-btn');
+  const landingLink = document.getElementById('menu-landing-link');
   const signinLink = document.getElementById('menu-signin-link');
   const noSessNote = document.getElementById('menu-no-session-note');
 
@@ -3955,6 +3956,7 @@ function initAccountCard() {
 
     signoutBtn.classList.remove('d-none');
     signoutBtn.addEventListener('click', () => handleSignOut(session), { once: false });
+    landingLink?.classList.remove('d-none');   // stay-signed-in route to the hub
     signinLink?.classList.add('d-none');
     noSessNote?.classList.add('d-none');
     menuBtn.removeAttribute('data-state');
@@ -3968,6 +3970,7 @@ function initAccountCard() {
     detailEl.textContent = '';
 
     signoutBtn.classList.add('d-none');
+    landingLink?.classList.add('d-none');
     signinLink?.classList.add('d-none');
     noSessNote?.classList.remove('d-none');
     menuBtn.dataset.state = 'no-session';
@@ -3981,6 +3984,7 @@ function initAccountCard() {
     detailEl.textContent = '';
 
     signoutBtn.classList.add('d-none');
+    landingLink?.classList.add('d-none');   // sign-in link below already points to the hub
     signinLink?.classList.remove('d-none');
     noSessNote?.classList.add('d-none');
     menuBtn.dataset.state = 'unauthenticated';