feat: [roadmap] 중장기 계획 메뉴 및 전용 페이지 개발

- 모델: AdminRoadmapPlan, AdminRoadmapMilestone
- 서비스: RoadmapPlanService, RoadmapMilestoneService
- FormRequest: Store/Update Plan/Milestone 4개
- 컨트롤러: Blade(RoadmapController), API(Plan/Milestone) 3개
- 라우트: web.php, api.php에 roadmap 라우트 추가
- Blade 뷰: 대시보드, 목록, 생성, 수정, 상세, 파셜 테이블 6개
- HTMX 기반 필터링/페이지네이션, 마일스톤 인라인 추가/토글

app/Http/Controllers/Api/Admin/Roadmap/RoadmapPlanController.php

@@ -0,0 +1,130 @@
+<?php
+
+namespace App\Http\Controllers\Api\Admin\Roadmap;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\Roadmap\StorePlanRequest;
+use App\Http\Requests\Roadmap\UpdatePlanRequest;
+use App\Services\Roadmap\RoadmapPlanService;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\View\View;
+
+class RoadmapPlanController extends Controller
+{
+    public function __construct(
+        private readonly RoadmapPlanService $planService
+    ) {}
+
+    public function index(Request $request): View|JsonResponse
+    {
+        $filters = $request->only([
+            'search', 'status', 'category', 'priority', 'phase',
+            'trashed', 'sort_by', 'sort_direction',
+        ]);
+        $plans = $this->planService->getPlans($filters, 15);
+
+        if ($request->header('HX-Request')) {
+            return view('roadmap.plans.partials.table', compact('plans'));
+        }
+
+        return response()->json([
+            'success' => true,
+            'data' => $plans,
+        ]);
+    }
+
+    public function stats(): JsonResponse
+    {
+        $stats = $this->planService->getStats();
+
+        return response()->json([
+            'success' => true,
+            'data' => $stats,
+        ]);
+    }
+
+    public function timeline(Request $request): JsonResponse
+    {
+        $phase = $request->input('phase');
+        $timeline = $this->planService->getTimelineData($phase);
+
+        return response()->json([
+            'success' => true,
+            'data' => $timeline,
+        ]);
+    }
+
+    public function show(int $id): JsonResponse
+    {
+        $plan = $this->planService->getPlanById($id, true);
+
+        if (! $plan) {
+            return response()->json([
+                'success' => false,
+                'message' => '계획을 찾을 수 없습니다.',
+            ], 404);
+        }
+
+        return response()->json([
+            'success' => true,
+            'data' => $plan,
+        ]);
+    }
+
+    public function store(StorePlanRequest $request): JsonResponse
+    {
+        $plan = $this->planService->createPlan($request->validated());
+
+        return response()->json([
+            'success' => true,
+            'message' => '계획이 생성되었습니다.',
+            'data' => $plan,
+        ]);
+    }
+
+    public function update(UpdatePlanRequest $request, int $id): JsonResponse
+    {
+        $this->planService->updatePlan($id, $request->validated());
+
+        return response()->json([
+            'success' => true,
+            'message' => '계획이 수정되었습니다.',
+        ]);
+    }
+
+    public function destroy(int $id): JsonResponse
+    {
+        $this->planService->deletePlan($id);
+
+        return response()->json([
+            'success' => true,
+            'message' => '계획이 삭제되었습니다.',
+        ]);
+    }
+
+    public function restore(int $id): JsonResponse
+    {
+        $this->planService->restorePlan($id);
+
+        return response()->json([
+            'success' => true,
+            'message' => '계획이 복원되었습니다.',
+        ]);
+    }
+
+    public function changeStatus(Request $request, int $id): JsonResponse
+    {
+        $validated = $request->validate([
+            'status' => 'required|in:planned,in_progress,completed,delayed,cancelled',
+        ]);
+
+        $plan = $this->planService->changeStatus($id, $validated['status']);
+
+        return response()->json([
+            'success' => true,
+            'message' => '상태가 변경되었습니다.',
+            'data' => $plan,
+        ]);
+    }
+}