feat(auth-firebase): implement Phase 2 integration - Firebase Auth, Session Sync, Favorites Grid, and Firestore Newsletter

index.php

@@ -398,7 +398,14 @@ include __DIR__ . '/partials/head.php';
       <img src="<?php echo e($featured['hero']); ?>" alt="<?php echo e($featured['title']); ?>">
       <div class="hero-card__body">
         <p class="pill pill--gold"><?php echo e($t['featured']); ?></p>
-        <h3><?php echo e($featured['title']); ?></h3>
+        <div class="recipe__title-row">
+          <h3><?php echo e($featured['title']); ?></h3>
+          <button class="btn-favorite" data-slug="<?php echo e($featured['slug']); ?>" aria-label="Save to favorites">
+            <svg viewBox="0 0 24 24" stroke="currentColor" fill="none">
+              <path d="M20.84 4.61a5.5 5.5 0 0 0-7.78 0L12 5.67l-1.06-1.06a5.5 5.5 0 0 0-7.78 7.78l1.06 1.06L12 21.23l7.78-7.78 1.06-1.06a5.5 5.5 0 0 0 0-7.78z"></path>
+            </svg>
+          </button>
+        </div>
         <p><?php echo e($featured['description']); ?></p>
         <div class="meta">
           <span>⏱ <?php echo format_minutes((int)($featured['total_time'] ?? 0)); ?></span>
@@ -430,6 +437,11 @@ include __DIR__ . '/partials/head.php';
             <?php if (!empty($recipe['category'])): ?>
               <span class="pill pill--ghost"><?php echo e($recipe['category']); ?></span>
             <?php endif; ?>
+            <button class="btn-favorite" data-slug="<?php echo e($recipe['slug']); ?>" aria-label="Save to favorites" onclick="event.preventDefault(); event.stopPropagation();">
+              <svg viewBox="0 0 24 24" stroke="currentColor" fill="none">
+                <path d="M20.84 4.61a5.5 5.5 0 0 0-7.78 0L12 5.67l-1.06-1.06a5.5 5.5 0 0 0-7.78 7.78l1.06 1.06L12 21.23l7.78-7.78 1.06-1.06a5.5 5.5 0 0 0 0-7.78z"></path>
+              </svg>
+            </button>
           </a>
           <div class="card__body">
             <h3><a href="<?php echo e($recipeUrl($recipe)); ?>"><?php echo e($recipe['title']); ?></a></h3>