chore: disable GIN debug logging for consistent JSON output

- Set GIN to release mode (gin.SetMode(gin.ReleaseMode))
- Discard GIN default output (gin.DefaultWriter = io.Discard)
- All HTTP request logging now goes through RequestLog middleware which uses zap JSON output

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: wecoding

internal/api/router.go

@@ -5,6 +5,7 @@
 package api
 
 import (
+	"io"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
@@ -24,6 +25,10 @@ import (
 
 // NewRouter creates a new Gin router with all middleware and routes configured.
 func NewRouter(reg driver.Registry) *gin.Engine {
+	// Disable GIN debug logging and set to release mode
+	gin.SetMode(gin.ReleaseMode)
+	gin.DefaultWriter = io.Discard
+
 	r := gin.New()
 
 	// Global middleware