feat: initial blog engine with multi-language, profile, and role system

- Gin + GORM + Tailwind CSS blog engine
- OS-aware config (Linux /etc/blog_go/, Windows ./win/etc/blog_go/)
- SQLite by default, MySQL support via config
- Auto-migrate database + seed admin user on first run
- Session-based auth (login/logout)
- i18n: Chinese/English with auto-detect + manual switch
- Avatar dropdown nav with click-to-toggle menu
- Profile page: avatar upload, edit info, change password
- Role system: admin (full access) and author (profile only)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-contrib/sessions/cookie"
+	"github.com/gin-gonic/gin"
+
+	"go_blog/config"
+	"go_blog/handlers"
+	"go_blog/middleware"
+	"go_blog/models"
+)
+
+func main() {
+	// 1. Load configuration (auto-creates if missing).
+	cfg := config.LoadConfig()
+
+	// 2. Initialize the database (auto-migrates, seeds admin).
+	db := models.InitDB(cfg)
+
+	// 3. Create session store (cookie-based).
+	store := cookie.NewStore([]byte(cfg.Secret))
+	store.Options(sessions.Options{
+		Path:     "/",
+		MaxAge:   86400, // 24 hours
+		HttpOnly: true,  // prevent XSS access
+		Secure:   false, // set true in production with HTTPS
+	})
+
+	// 4. Create Gin router.
+	router := gin.Default()
+
+	// 5. Load HTML templates.
+	router.LoadHTMLGlob("templates/**/*.html")
+
+	// 6. Serve uploaded files (avatars etc.) from the storage path.
+	router.Static("/uploads", cfg.Path)
+
+	// 6. Global session middleware.
+	router.Use(sessions.Sessions("blog_session", store))
+
+	// 7. Global context middleware (sets IsLoggedIn, Username for templates).
+	router.Use(middleware.SetUserContext(db))
+
+	// 8. Register routes.
+	router.GET("/", handlers.HomePage())
+	router.GET("/login", handlers.LoginPage())
+	router.POST("/login", handlers.Login(db))
+	router.POST("/logout", handlers.Logout())
+
+	// Protected admin routes.
+	admin := router.Group("/admin")
+	admin.Use(middleware.AuthRequired())
+	{
+		admin.GET("", handlers.AdminDashboard())
+	}
+
+	// Protected profile routes.
+	profile := router.Group("/profile")
+	profile.Use(middleware.AuthRequired())
+	{
+		profile.GET("", handlers.ProfilePage(db))
+		profile.POST("", handlers.UpdateProfile(db, cfg.Path))
+	}
+
+	// 9. Start the server.
+	addr := fmt.Sprintf(":%s", cfg.Port)
+	log.Printf("Go Blog starting on http://localhost%s", addr)
+	if err := router.Run(addr); err != nil {
+		log.Fatalf("Failed to start server: %v", err)
+	}
+}