perf(rating): fetch-join comment tree to kill N+1 in public list (H7)

findApprovedRootsByDoctor used a plain findBy, so Comment::toArray() lazy-loaded
likes, replies and the author per comment (and recursively per reply). Hydrate
in two fetch-join passes (roots + author + likes; then replies + their author +
likes + one further reply level) — no per-comment lazy loads for a two-level
thread.

Regression: tests/Rating/CommentListNPlusOneTest (functional correctness — like
counts, approved-only replies, author preserved).

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

src/Rating/Repository/CommentRepository.php

@@ -22,10 +22,40 @@ class CommentRepository extends ServiceEntityRepository
     /** @return Comment[] approved root comments (no parent) for a doctor */
     public function findApprovedRootsByDoctor(Doctor $doctor): array
     {
-        return $this->findBy(
-            ['doctor' => $doctor, 'status' => Comment::STATUS_APPROVED, 'parent' => null],
-            ['createdAt' => 'DESC']
-        );
+        // Two fetch-join passes (not the product, to avoid a likes×replies
+        // cartesian) hydrate everything toArray() touches, so serialization
+        // triggers no per-comment lazy loads (N+1): pass 1 = roots + author +
+        // likes, pass 2 = replies + their author + likes, merged into the same
+        // managed root entities.
+        $roots = $this->createQueryBuilder('c')
+            ->addSelect('u', 'l')
+            ->leftJoin('c.user', 'u')
+            ->leftJoin('c.likes', 'l')
+            ->where('c.doctor = :doctor')
+            ->andWhere('c.status = :status')
+            ->andWhere('c.parent IS NULL')
+            ->setParameter('doctor', $doctor)
+            ->setParameter('status', Comment::STATUS_APPROVED)
+            ->orderBy('c.createdAt', 'DESC')
+            ->getQuery()
+            ->getResult();
+
+        if ($roots !== []) {
+            // Also initialise each reply's own replies collection (empty in a
+            // two-level thread) so reply->toArray() doesn't lazy-load it per row.
+            $this->createQueryBuilder('c')
+                ->addSelect('r', 'ru', 'rl', 'rr')
+                ->leftJoin('c.replies', 'r')
+                ->leftJoin('r.user', 'ru')
+                ->leftJoin('r.likes', 'rl')
+                ->leftJoin('r.replies', 'rr')
+                ->where('c IN (:roots)')
+                ->setParameter('roots', $roots)
+                ->getQuery()
+                ->getResult();
+        }
+
+        return $roots;
     }
 
     /** @return Comment[] */