feat(iap): 移除苹果IAP商品列表接口并添加接入指南文档

移除不再使用的苹果IAP商品列表相关代码，包括handler、logic和测试文件
新增详细的iOS内购接入指南文档，包含StoreKit2使用流程和接口规范

internal/logic/public/iap/apple/getProductsLogic.go

@@ -1,42 +0,0 @@
-package apple
-
-import (
-	"context"
-
-	"github.com/perfect-panel/server/internal/svc"
-	"github.com/perfect-panel/server/internal/types"
-	"github.com/perfect-panel/server/pkg/logger"
-	iapapple "github.com/perfect-panel/server/pkg/iap/apple"
-)
-
-type GetProductsLogic struct {
-	logger.Logger
-	ctx    context.Context
-	svcCtx *svc.ServiceContext
-}
-
-func NewGetProductsLogic(ctx context.Context, svcCtx *svc.ServiceContext) *GetProductsLogic {
-	return &GetProductsLogic{
-		Logger: logger.WithContext(ctx),
-		ctx:    ctx,
-		svcCtx: svcCtx,
-	}
-}
-
-func (l *GetProductsLogic) GetProducts() (*types.GetAppleProductsResponse, error) {
-	pm, _ := iapapple.ParseProductMap(l.svcCtx.Config.Site.CustomData)
-	resp := &types.GetAppleProductsResponse{
-		List: make([]types.AppleProduct, 0, len(pm.Items)),
-	}
-	for pid, m := range pm.Items {
-		resp.List = append(resp.List, types.AppleProduct{
-			ProductId:    pid,
-			Description:  m.Description,
-			PriceText:    m.PriceText,
-			DurationDays: m.DurationDays,
-			Tier:         m.Tier,
-			SubscribeId:  m.SubscribeId,
-		})
-	}
-	return resp, nil
-}