Refactor home screen to use actual service data

[Copilot]

Overview

The home screen endpoint was returning mock data with TODO comments. This refactor integrates four existing services to provide real, personalized content.

Changes

Service Integration

• BannerService: Personalized banners (review prompts, magazine recommendations)
• AdvertisementService: Promotional content
• ProductService: Recommendation engine (personalized for logged-in users, popular for anonymous)
• MagazineService: Curated content

DTO Updates

HomeResDto now returns typed domain objects instead of string lists:

// Before
List<String> bannerUrls
List<String> recommendProducts
String latestMagazineTitle

// After  
BannerResponse banner
List<AdvertisementResponse> advertisements
List<RecommendedProductResponse> recommendedProducts
List<MagazineResDto> recommendedMagazines

Controller Enhancement

HomeController now accepts @AuthenticationPrincipal Long userId to enable personalized recommendations while maintaining support for anonymous users (userId = null).

Technical Notes

• All injected services use @Transactional(readOnly = true)
• Recommendation size hardcoded to 10 products (could be configurable)
• Import ordering follows standard Java conventions (java., org., com.*)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Refactor] 홈화면</issue_title>
<issue_description>## 📌 Description

[Refactor] 홈화면

✅ To-do

• 진행 예정
• 진행 완료

📒 기타</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Refactor] 홈화면 #97

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