feat: 添加应用骨架，配置化 zap 日志贯穿全链路

- cmd/server/main.go: 使用 logger.NewLogger(cfg.Log) 替代 zap.NewProduction()

- internal/app: 依赖注入组装 DB/Slurm/Service/Handler，传递 logger

- internal/middleware: RequestLogger 请求日志中间件

- internal/server: 统一响应格式和路由注册

- go.mod: module 更名为 gcy_hpc_server，添加 gin/zap/lumberjack/gorm 依赖

- 日志初始化失败时 fail fast (os.Exit(1))

- GormLevel 从配置传递到 NewGormDB，支持 YAML 独立配置

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/app/app_test.go

@@ -0,0 +1,25 @@
+package app
+
+import (
+	"testing"
+
+	"gcy_hpc_server/internal/config"
+
+	"go.uber.org/zap/zaptest"
+)
+
+func TestNewApp_InvalidDB(t *testing.T) {
+	cfg := &config.Config{
+		ServerPort:      "8080",
+		MySQLDSN:        "invalid:dsn@tcp(localhost:99999)/nonexistent?parseTime=true",
+		SlurmAPIURL:     "http://localhost:6820",
+		SlurmUserName:   "root",
+		SlurmJWTKeyPath: "/nonexistent/jwt.key",
+	}
+	logger := zaptest.NewLogger(t)
+
+	_, err := NewApp(cfg, logger)
+	if err == nil {
+		t.Fatal("expected error for invalid DSN, got nil")
+	}
+}