feat(comment): 게시글 댓글 CRUD 기능 추가

- 댓글 라우트 추가 (store, update, destroy)
- PostService에 댓글 관리 메서드 추가
- PostController에 댓글 컨트롤러 메서드 추가
- 게시글 상세 페이지에 댓글 섹션 UI 추가 (AlpineJS)
- 계층형 댓글 지원 (부모/대댓글)
- BoardComment 모델 추가
- HTMLPurifier 패키지 및 설정 추가
- 게시글 목록에 첨부파일/댓글 수 표시

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Models/Boards/BoardComment.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace App\Models\Boards;
+
+use App\Models\User;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+/**
+ * 게시글 댓글 모델
+ *
+ * @property int $id
+ * @property int $post_id
+ * @property int|null $tenant_id
+ * @property int $user_id
+ * @property int|null $parent_id
+ * @property string $content
+ * @property string|null $ip_address
+ * @property string $status
+ */
+class BoardComment extends Model
+{
+    use SoftDeletes;
+
+    protected $table = 'board_comments';
+
+    protected $fillable = [
+        'post_id',
+        'tenant_id',
+        'user_id',
+        'parent_id',
+        'content',
+        'ip_address',
+        'status',
+    ];
+
+    // =========================================================================
+    // Relationships
+    // =========================================================================
+
+    public function post(): BelongsTo
+    {
+        return $this->belongsTo(Post::class, 'post_id');
+    }
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'user_id');
+    }
+
+    public function parent(): BelongsTo
+    {
+        return $this->belongsTo(BoardComment::class, 'parent_id');
+    }
+
+    public function children(): HasMany
+    {
+        return $this->hasMany(BoardComment::class, 'parent_id')
+            ->where('status', 'active');
+    }
+
+    /**
+     * Alias for children() - used for eager loading
+     */
+    public function replies(): HasMany
+    {
+        return $this->children();
+    }
+}