feat(API): Position API 추가 (직급/직책 통합)

- Position 모델 생성 (type: rank | title)
- PositionService: CRUD + reorder 구현
- PositionController: REST API 엔드포인트
- Swagger 문서 작성 (PositionApi.php)
- 마이그레이션: positions 테이블 + common_codes 등록
- routes/api.php에 라우트 등록

Phase L-3 (직급관리), L-4 (직책관리) 백엔드 완료

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

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

app/Http/Requests/PositionRequest.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace App\Http\Requests;
+
+use App\Models\Tenants\Position;
+use Illuminate\Foundation\Http\FormRequest;
+use Illuminate\Validation\Rule;
+
+class PositionRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        $method = $this->method();
+
+        if ($method === 'GET') {
+            return [
+                'type' => ['nullable', Rule::in([Position::TYPE_RANK, Position::TYPE_TITLE])],
+                'is_active' => 'nullable|boolean',
+                'q' => 'nullable|string|max:100',
+                'per_page' => 'nullable|integer|min:1|max:100',
+                'page' => 'nullable|integer|min:1',
+            ];
+        }
+
+        if ($method === 'POST') {
+            return [
+                'type' => ['required', Rule::in([Position::TYPE_RANK, Position::TYPE_TITLE])],
+                'name' => 'required|string|max:50',
+                'sort_order' => 'nullable|integer|min:0',
+                'is_active' => 'nullable|boolean',
+            ];
+        }
+
+        if (in_array($method, ['PUT', 'PATCH'])) {
+            return [
+                'name' => 'nullable|string|max:50',
+                'sort_order' => 'nullable|integer|min:0',
+                'is_active' => 'nullable|boolean',
+            ];
+        }
+
+        return [];
+    }
+
+    public function messages(): array
+    {
+        return [
+            'type.required' => __('validation.required', ['attribute' => '유형']),
+            'type.in' => __('validation.in', ['attribute' => '유형']),
+            'name.required' => __('validation.required', ['attribute' => '명칭']),
+            'name.max' => __('validation.max.string', ['attribute' => '명칭', 'max' => 50]),
+        ];
+    }
+}