Add Rosary Builder — custom prayer-sequence sessions

Superuser+ can now build a custom prayer sequence from scratch:
- Two-panel builder UI: step sequence (left) + searchable prayer library (right)
- 16 standard prayers seeded globally; users can create private custom prayers
- Admin can promote private prayers to global and manage the library
- Four attribution modes per step: Leader/All, Leader only, All together, None
- Optional subject name/pronoun for variable substitution in prayers
- Custom sessions fully presented via the existing presenter (auto-split works)
- migrate_v4.php creates custom_prayers + builder_steps tables

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

admin/index.php

@@ -94,6 +94,7 @@ $occasion_labels = [
     'divine_mercy_novena' => 'Divine Mercy Novena',
     'general_rosary'      => 'General Rosary',
     'memorial'            => 'Memorial',
+    'custom'              => 'Custom Sequence',
 ];
 $mystery_labels = [
     'sorrowful'      => 'Sorrowful',
@@ -121,7 +122,11 @@ $novena_created = isset($_GET['novena_created']) ? (int)$_GET['novena_created']
         <h1>&#x271D; <?= htmlspecialchars($site_name) ?></h1>
         <div class="header-actions">
             <a href="<?= BASE_URL ?>/" class="btn btn-ghost" style="font-size:13px">&#x2190; View Site</a>
+            <?php if (has_role('superuser')): ?>
+                <a href="<?= BASE_URL ?>/admin/builder.php" class="btn btn-ghost">&#x2712; Builder</a>
+            <?php endif; ?>
             <?php if (has_role('admin')): ?>
+                <a href="<?= BASE_URL ?>/admin/prayers.php" class="btn btn-ghost">Prayers</a>
                 <a href="<?= BASE_URL ?>/admin/users.php" class="btn btn-ghost">Users</a>
                 <a href="<?= BASE_URL ?>/admin/audio.php" class="btn btn-ghost">Audio</a>
             <?php endif; ?>
@@ -142,7 +147,12 @@ $novena_created = isset($_GET['novena_created']) ? (int)$_GET['novena_created']
 
         <div style="display:flex;justify-content:space-between;align-items:center;margin-bottom:20px">
             <h2 style="margin:0"><?= $is_admin ? 'All Sessions' : 'My Sessions' ?></h2>
-            <a href="<?= BASE_URL ?>/admin/setup.php" class="btn btn-primary">+ New Session</a>
+            <div style="display:flex;gap:8px">
+                <?php if (has_role('superuser')): ?>
+                <a href="<?= BASE_URL ?>/admin/builder.php" class="btn btn-secondary">&#x2712; Build Custom</a>
+                <?php endif; ?>
+                <a href="<?= BASE_URL ?>/admin/setup.php" class="btn btn-primary">+ New Session</a>
+            </div>
         </div>
 
         <?php if (empty($all_rows)): ?>
@@ -224,7 +234,10 @@ $novena_created = isset($_GET['novena_created']) ? (int)$_GET['novena_created']
                            target="_blank"
                            class="btn btn-sm btn-primary">Present</a>
                         <?php if ($is_admin || (int)$row['user_id'] === $uid): ?>
-                        <a href="<?= BASE_URL ?>/admin/setup.php?id=<?= $row['id'] ?>"
+                        <?php $edit_url = ($row['occasion'] === 'custom')
+                            ? BASE_URL . '/admin/builder.php?id=' . $row['id']
+                            : BASE_URL . '/admin/setup.php?id=' . $row['id']; ?>
+                        <a href="<?= htmlspecialchars($edit_url) ?>"
                            class="btn btn-sm btn-secondary">Edit</a>
                         <form method="post" style="display:inline"
                               onsubmit="return confirm('Delete this session?')">