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/Controllers/Api/V1/PositionController.php

@@ -0,0 +1,74 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\PositionReorderRequest;
+use App\Http\Requests\PositionRequest;
+use App\Services\PositionService;
+
+class PositionController extends Controller
+{
+    public function __construct(private PositionService $service) {}
+
+    /**
+     * GET /v1/positions
+     */
+    public function index(PositionRequest $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->index($request->validated());
+        }, __('message.fetched'));
+    }
+
+    /**
+     * POST /v1/positions
+     */
+    public function store(PositionRequest $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->store($request->validated());
+        }, __('message.created'));
+    }
+
+    /**
+     * GET /v1/positions/{id}
+     */
+    public function show(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            return $this->service->show($id);
+        }, __('message.fetched'));
+    }
+
+    /**
+     * PUT /v1/positions/{id}
+     */
+    public function update(int $id, PositionRequest $request)
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->update($id, $request->validated());
+        }, __('message.updated'));
+    }
+
+    /**
+     * DELETE /v1/positions/{id}
+     */
+    public function destroy(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            return $this->service->destroy($id);
+        }, __('message.deleted'));
+    }
+
+    /**
+     * PUT /v1/positions/reorder
+     */
+    public function reorder(PositionReorderRequest $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->reorder($request->validated()['items']);
+        }, __('message.reordered'));
+    }
+}