Fix stale DB connections, add Why Bourbonacci section, harden auth

- Add pool_pre_ping and pool_recycle to prevent lost connection errors on idle pool
- Add Why Bourbonacci card to about page
- Redirect to login on 401 in API layer
- Check JWT expiry in isLoggedIn instead of just token presence

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/about.html

@@ -21,6 +21,19 @@
 
   <h1 class="page-title">What is an Infinity Bottle?</h1>
 
+  <div class="card" style="margin-bottom:1.5rem">
+    <div class="card-title">Why Bourbonacci?</div>
+    <p style="color:var(--cream);line-height:1.8;margin-bottom:1rem">
+      The name is a blend of two things: <strong style="color:var(--amber-light)">Bourbon</strong> and the <strong style="color:var(--amber-light)">Fibonacci sequence</strong>.
+    </p>
+    <p style="color:var(--cream);line-height:1.8;margin-bottom:1rem">
+      The Fibonacci sequence — 1, 1, 2, 3, 5, 8, 13… — is a series where each number is the sum of the two before it. It goes on forever, building endlessly on everything that came before it. An infinity bottle works the same way: every addition builds on the blend that already exists, and the result is something that compounds in complexity over time with no defined end.
+    </p>
+    <p style="color:var(--cream);line-height:1.8">
+      Just as no two numbers in the sequence are the same, no two infinity bottles are alike — and just like the sequence itself, yours will never truly be finished.
+    </p>
+  </div>
+
   <div class="card" style="margin-bottom:1.5rem">
     <div class="card-title">The Concept</div>
     <p style="color:var(--cream);line-height:1.8;margin-bottom:1rem">

frontend/js/api.js

@@ -26,6 +26,13 @@ const API = (() => {
 
     const data = await res.json().catch(() => null);
 
+    if (res.status === 401) {
+      localStorage.removeItem('bb_token');
+      localStorage.removeItem('bb_user');
+      window.location.href = '/login.html';
+      return;
+    }
+
     if (!res.ok) {
       const msg = data?.detail || `HTTP ${res.status}`;
       throw new Error(Array.isArray(msg) ? msg.map(e => e.msg).join(', ') : msg);

frontend/js/auth.js

@@ -26,7 +26,11 @@ const Auth = (() => {
     window.location.href = '/login.html';
   }
 
-  function isLoggedIn() { return !!getToken(); }
+  function isLoggedIn() {
+    const payload = _decodePayload();
+    if (!payload) return false;
+    return payload.exp * 1000 > Date.now();
+  }
 
   function requireAuth() {
     if (!isLoggedIn()) {