feat: 블록체인(chain) 통합 및 내부 API 추가

- internal/chain 패키지 추가 (client, handler, service, repository, model)
- 체인 연동 엔드포인트: 지갑 조회, 잔액, 자산, 인벤토리, 마켓 등
- 관리자 전용 체인 엔드포인트: 민팅, 보상, 템플릿 등록
- 게임 서버용 내부 API (/api/internal/chain/*) + ServerAuth 미들웨어
- 회원가입 시 블록체인 월렛 자동 생성
- 체인 관련 환경변수 및 InternalAPIKey 설정 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

routes/routes.go

@@ -3,6 +3,7 @@ package routes
 import (
 	"a301_server/internal/announcement"
 	"a301_server/internal/auth"
+	"a301_server/internal/chain"
 	"a301_server/internal/download"
 	"a301_server/pkg/middleware"
 	"github.com/gofiber/fiber/v2"
@@ -13,6 +14,7 @@ func Register(
 	authH *auth.Handler,
 	annH *announcement.Handler,
 	dlH *download.Handler,
+	chainH *chain.Handler,
 ) {
 	api := app.Group("/api")
 
@@ -43,4 +45,37 @@ func Register(
 	dl.Get("/launcher", dlH.ServeLauncher)
 	dl.Post("/upload/game", middleware.Auth, middleware.AdminOnly, dlH.Upload)
 	dl.Post("/upload/launcher", middleware.Auth, middleware.AdminOnly, dlH.UploadLauncher)
+
+	// Chain - Queries (authenticated)
+	ch := api.Group("/chain", middleware.Auth)
+	ch.Get("/wallet", chainH.GetWalletInfo)
+	ch.Get("/balance", chainH.GetBalance)
+	ch.Get("/assets", chainH.GetAssets)
+	ch.Get("/asset/:id", chainH.GetAsset)
+	ch.Get("/inventory", chainH.GetInventory)
+	ch.Get("/market", chainH.GetMarketListings)
+	ch.Get("/market/:id", chainH.GetMarketListing)
+
+	// Chain - User Transactions (authenticated)
+	ch.Post("/transfer", chainH.Transfer)
+	ch.Post("/asset/transfer", chainH.TransferAsset)
+	ch.Post("/market/list", chainH.ListOnMarket)
+	ch.Post("/market/buy", chainH.BuyFromMarket)
+	ch.Post("/market/cancel", chainH.CancelListing)
+	ch.Post("/inventory/equip", chainH.EquipItem)
+	ch.Post("/inventory/unequip", chainH.UnequipItem)
+
+	// Chain - Admin Transactions (admin only)
+	chainAdmin := api.Group("/chain/admin", middleware.Auth, middleware.AdminOnly)
+	chainAdmin.Post("/mint", chainH.MintAsset)
+	chainAdmin.Post("/reward", chainH.GrantReward)
+	chainAdmin.Post("/template", chainH.RegisterTemplate)
+
+	// Internal - Game server endpoints (API key auth, username-based)
+	internal := api.Group("/internal/chain", middleware.ServerAuth)
+	internal.Post("/reward", chainH.InternalGrantReward)
+	internal.Post("/mint", chainH.InternalMintAsset)
+	internal.Get("/balance", chainH.InternalGetBalance)
+	internal.Get("/assets", chainH.InternalGetAssets)
+	internal.Get("/inventory", chainH.InternalGetInventory)
 }