fix: log management race condition, partial delete reporting, and UX issues

- Fix data race on gin.DefaultWriter during log rotation by adding LogWriterMu
- Report partial failure when some log files fail to delete instead of always returning success
- Fix misleading "logging disabled" banner shown before API responds
- Fix en.json translation for numeric validation message

common/sys_log.go

@@ -3,53 +3,60 @@ package common
 import (
 	"fmt"
 	"os"
+	"sync"
 	"time"
 
 	"github.com/gin-gonic/gin"
 )
 
+// LogWriterMu protects concurrent access to gin.DefaultWriter/gin.DefaultErrorWriter
+// during log file rotation. Acquire RLock when reading/writing through the writers,
+// acquire Lock when swapping writers and closing old files.
+var LogWriterMu sync.RWMutex
+
 func SysLog(s string) {
 	t := time.Now()
+	LogWriterMu.RLock()
 	_, _ = fmt.Fprintf(gin.DefaultWriter, "[SYS] %v | %s \n", t.Format("2006/01/02 - 15:04:05"), s)
+	LogWriterMu.RUnlock()
 }
 
 func SysError(s string) {
 	t := time.Now()
+	LogWriterMu.RLock()
 	_, _ = fmt.Fprintf(gin.DefaultErrorWriter, "[SYS] %v | %s \n", t.Format("2006/01/02 - 15:04:05"), s)
+	LogWriterMu.RUnlock()
 }
 
 func FatalLog(v ...any) {
 	t := time.Now()
+	LogWriterMu.RLock()
 	_, _ = fmt.Fprintf(gin.DefaultErrorWriter, "[FATAL] %v | %v \n", t.Format("2006/01/02 - 15:04:05"), v)
+	LogWriterMu.RUnlock()
 	os.Exit(1)
 }
 
 func LogStartupSuccess(startTime time.Time, port string) {
-
 	duration := time.Since(startTime)
 	durationMs := duration.Milliseconds()
 
 	// Get network IPs
 	networkIps := GetNetworkIps()
 
-	// Print blank line for spacing
-	fmt.Fprintf(gin.DefaultWriter, "\n")
+	LogWriterMu.RLock()
+	defer LogWriterMu.RUnlock()
 
-	// Print the main success message
+	fmt.Fprintf(gin.DefaultWriter, "\n")
 	fmt.Fprintf(gin.DefaultWriter, "  \033[32m%s %s\033[0m  ready in %d ms\n", SystemName, Version, durationMs)
 	fmt.Fprintf(gin.DefaultWriter, "\n")
 
-	// Skip fancy startup message in container environments
 	if !IsRunningInContainer() {
-		// Print local URL
 		fmt.Fprintf(gin.DefaultWriter, "  ➜  \033[1mLocal:\033[0m   http://localhost:%s/\n", port)
 	}
 
-	// Print network URLs
 	for _, ip := range networkIps {
 		fmt.Fprintf(gin.DefaultWriter, "  ➜  \033[1mNetwork:\033[0m http://%s:%s/\n", ip, port)
 	}
 
-	// Print blank line for spacing
 	fmt.Fprintf(gin.DefaultWriter, "\n")
 }