feat(backend,docker,docs): implement Go/Gin/SQLite REST API server, Docker containerization, and architecture specifications

- Implement standalone Go backend API server using Gin and pure-Go SQLite (modernc.org/sqlite)
- Add 11-table schema DDL migrations (000001_init.up.sql) based on DATA_TABLE.md
- Add seed data ingestion tool (cmd/seed) and static TypeScript content exporter (cmd/export-content)
- Add configuration loader (internal/config) supporting environment variables and .env files (HOST, PORT, DB_PATH, GIN_MODE, CORS_ALLOW_ORIGINS, AUTO_MIGRATE)
- Add lightweight multi-stage Dockerfile and docker-compose.yml with persistent SQLite volume
- Add comprehensive architecture specification (ARCHITECTURE.md) and REST API interface specification (API_INTERFACE.md)
- Harmonize frontend publications page to consume isHighlight flag from database-synced content

backend/cmd/api/main.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"flag"
+	"log"
+
+	"git.godopu.com/lab/landing_page/backend/internal/config"
+	"git.godopu.com/lab/landing_page/backend/internal/db"
+	"git.godopu.com/lab/landing_page/backend/internal/router"
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	// Load environment variables & .env
+	cfg := config.Load()
+
+	// Optional CLI flags override environment defaults
+	portFlag := flag.Int("port", 0, "Port for the Gin server to listen on (overrides PORT)")
+	hostFlag := flag.String("host", "", "Host for the Gin server to bind on (overrides HOST)")
+	dbPathFlag := flag.String("db", "", "Path to SQLite database file (overrides DB_PATH)")
+	ginModeFlag := flag.String("mode", "", "Gin mode: release, debug, test (overrides GIN_MODE)")
+	flag.Parse()
+
+	if *portFlag > 0 {
+		cfg.Port = *portFlag
+	}
+	if *hostFlag != "" {
+		cfg.Host = *hostFlag
+	}
+	if *dbPathFlag != "" {
+		cfg.DBPath = *dbPathFlag
+	}
+	if *ginModeFlag != "" {
+		cfg.GinMode = *ginModeFlag
+	}
+
+	gin.SetMode(cfg.GinMode)
+
+	log.Printf("Connecting to SQLite database at %s...", cfg.DBPath)
+	database, err := db.Connect(cfg.DBPath)
+	if err != nil {
+		log.Fatalf("Failed to connect to database: %v", err)
+	}
+	defer database.Close()
+
+	if cfg.AutoMigrate {
+		log.Println("Ensuring database schema migrations are applied...")
+		if err := db.RunMigrations(database); err != nil {
+			log.Fatalf("Migration failed: %v", err)
+		}
+	}
+
+	r := router.SetupRouter(database, cfg.CORSAllowOrigins)
+
+	addr := cfg.Address()
+	log.Printf("Starting ANL Backend API server on http://%s/api/v1 (mode: %s)...", addr, cfg.GinMode)
+	if err := r.Run(addr); err != nil {
+		log.Fatalf("Server failed to run: %v", err)
+	}
+}