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>

includes/build_slides.php

@@ -10,6 +10,21 @@
 
 require_once __DIR__ . '/../data/prayers.php';
 
+/**
+ * Fetch ordered builder steps (with prayer text) for a custom session.
+ */
+function get_builder_steps(PDO $pdo, int $session_id): array {
+    $st = $pdo->prepare("
+        SELECT bs.attribution, cp.name, cp.leader_text, cp.all_text
+        FROM   builder_steps bs
+        JOIN   custom_prayers cp ON cp.id = bs.prayer_id
+        WHERE  bs.session_id = ?
+        ORDER  BY bs.step_order ASC
+    ");
+    $st->execute([$session_id]);
+    return $st->fetchAll();
+}
+
 /**
  * Returns the slide array for one decade of the Chaplet of Divine Mercy.
  *
@@ -65,6 +80,91 @@ function build_slides(array $session): array {
 
     $slides = [];
 
+    // -----------------------------------------------------------------------
+    // Custom builder session — build directly from builder_steps
+    // -----------------------------------------------------------------------
+    if ($session['occasion'] === 'custom') {
+        $pdo   = get_pdo();
+        $steps = get_builder_steps($pdo, (int)$session['id']);
+
+        // Cover slide
+        $cover_all = '';
+        if (!empty($session['subject_name'])) {
+            $cover_all = "For {$session['subject_name']}";
+        }
+        $slides[] = [
+            'id'         => 'cover',
+            'type'       => 'cover',
+            'section'    => 'cover',
+            'title'      => $session['name'],
+            'leader'     => '',
+            'all'        => $cover_all,
+            'bead'       => null,
+            'bead_index' => null,
+            'photo_path' => $session['photo_path'] ?? null,
+        ];
+
+        foreach ($steps as $i => $step) {
+            $attr   = $step['attribution'];
+            $leader = '';
+            $all    = '';
+
+            if ($attr === 'leader_all' || $attr === 'leader_only') {
+                $leader = $step['leader_text'] ?? '';
+            }
+            if ($attr === 'leader_all' || $attr === 'all_only') {
+                $all = $step['all_text'] ?? '';
+            }
+            if ($attr === 'none') {
+                // Show prayer text without attribution labels — put in leader field
+                $leader = ($step['leader_text'] ?: $step['all_text']) ?? '';
+            }
+
+            $slides[] = [
+                'id'         => 'custom_' . $i,
+                'type'       => 'prayer',
+                'section'    => $step['name'],
+                'title'      => $step['name'],
+                'leader'     => $leader,
+                'all'        => $all,
+                'bead'       => null,
+                'bead_index' => null,
+            ];
+        }
+
+        // Closing slide
+        $slides[] = [
+            'id'         => 'closing_custom',
+            'type'       => 'closing',
+            'section'    => 'closing',
+            'title'      => '',
+            'leader'     => '',
+            'all'        => "May the souls of the faithful departed,\nthrough the mercy of God, rest in peace.",
+            'bead'       => null,
+            'bead_index' => null,
+        ];
+
+        // Apply variable substitution and return early
+        $name    = $session['subject_name']    ?? '';
+        $pronoun = $session['subject_pronoun'] ?? 'he';
+        $dates   = $session['subject_dates']   ?? '';
+
+        $pronoun_obj  = ($pronoun === 'she') ? 'her' : 'him';
+        $pronoun_poss = ($pronoun === 'she') ? 'her' : 'his';
+
+        $find    = ['{name}', '{pronoun}', '{pronoun_obj}', '{pronoun_poss}', '{subject_dates}'];
+        $replace = [$name,    $pronoun,    $pronoun_obj,    $pronoun_poss,    $dates];
+
+        foreach ($slides as &$slide) {
+            $slide['title']  = str_replace($find, $replace, $slide['title']  ?? '');
+            $slide['leader'] = str_replace($find, $replace, $slide['leader'] ?? '');
+            $slide['all']    = str_replace($find, $replace, $slide['all']    ?? '');
+        }
+        unset($slide);
+
+        return $slides;
+    }
+
     // -----------------------------------------------------------------------
     // 1. Cover slide
     // -----------------------------------------------------------------------