feat: add DB_TIMEZONE configuration and update logging for PostgreSQL timezone

main.go

@@ -22,6 +22,7 @@ package main
 import (
 	"fmt"
 	"log"
+	"net/url"
 	"os"
 	"path/filepath"
 
@@ -67,7 +68,11 @@ func main() {
 			dialector = sqlite.Open(dsn)
 			dbEngine = "sqlite"
 		default:
-			dialector = postgres.Open(cfg.PostgresDSN)
+			dsn := cfg.PostgresDSN
+			if cfg.DBTimezone != "" {
+				dsn = appendQueryParam(dsn, "timezone", cfg.DBTimezone)
+			}
+			dialector = postgres.Open(dsn)
 		}
 
 		var err error
@@ -161,9 +166,27 @@ func main() {
 		log.Printf("   DB logging      : enabled")
 	}
 	log.Printf("   SSE streaming   : %v", cfg.Streaming)
+	if cfg.DBTimezone != "" {
+		log.Printf("   DB timezone     : %s", cfg.DBTimezone)
+	}
 
 	if err := app.Listen(addr); err != nil {
 		log.Fatalf("server error: %v", err)
 		os.Exit(1)
 	}
 }
+
+func appendQueryParam(dsn, key, value string) string {
+	if value == "" {
+		return dsn
+	}
+	u, err := url.Parse(dsn)
+	if err != nil {
+		log.Printf("⚠️  Failed to parse DSN for timezone: %v", err)
+		return dsn
+	}
+	q := u.Query()
+	q.Set(key, value)
+	u.RawQuery = q.Encode()
+	return u.String()
+}