style: adopt golangci-lint v2 and resolve all findings

Add .golangci.yml (v2): the standard linters plus bodyclose, errorlint, noctx, misspell, rowserrcheck, sqlclosecheck, unconvert, usestdlibvars, with gofumpt + goimports formatters. Enable the std-error-handling exclusion preset for idiomatic Close/Remove/Setenv ignores; scope-exclude SA1019 (parser.ParseDir in tools/openapigen) and ST1005 (intentional capitalized user-facing error copy that tests assert verbatim). No inline nolint directives were introduced.

Resolve all 217 findings behavior-preserving: gofumpt/goimports formatting, explicit blank assignment on intentionally ignored errors, errors.Is/errors.As and %w wrapping, context-aware stdlib calls (CommandContext/QueryContext/NewRequestWithContext/Dialer), staticcheck simplifications, removed redundant conversions, http.StatusOK and http.MethodGet, inlined the go:fix intPtr helper, and deferred sql rows Close. Add a golangci CI job mirroring the existing Go jobs.

internal/web/controller/api.go

@@ -5,7 +5,6 @@ import (
 	"strings"
 
 	"github.com/mhsanaei/3x-ui/v3/internal/web/middleware"
-	"github.com/mhsanaei/3x-ui/v3/internal/web/service"
 	"github.com/mhsanaei/3x-ui/v3/internal/web/service/panel"
 	"github.com/mhsanaei/3x-ui/v3/internal/web/service/tgbot"
 	"github.com/mhsanaei/3x-ui/v3/internal/web/session"
@@ -22,7 +21,6 @@ type APIController struct {
 	hostController        *HostController
 	settingController     *SettingController
 	xraySettingController *XraySettingController
-	settingService        service.SettingService
 	userService           panel.UserService
 	apiTokenService       panel.ApiTokenService
 	Tgbot                 tgbot.Tgbot

internal/web/controller/inbound.go

@@ -61,7 +61,6 @@ func (a *InboundController) broadcastInboundsUpdate(userId int) {
 
 // initRouter initializes the routes for inbound-related operations.
 func (a *InboundController) initRouter(g *gin.RouterGroup) {
-
 	g.GET("/list", a.getInbounds)
 	g.GET("/list/slim", a.getInboundsSlim)
 	g.GET("/options", a.getInboundOptions)

internal/web/controller/server.go

@@ -42,7 +42,6 @@ func NewServerController(g *gin.RouterGroup) *ServerController {
 
 // initRouter sets up the routes for server status, Xray management, and utility endpoints.
 func (a *ServerController) initRouter(g *gin.RouterGroup) {
-
 	g.GET("/status", a.status)
 	g.GET("/cpuHistory/:bucket", a.getCpuHistoryBucket)
 	g.GET("/history/:metric/:bucket", a.getMetricHistoryBucket)
@@ -89,7 +88,7 @@ func (a *ServerController) initRouter(g *gin.RouterGroup) {
 // the cross-service side effects (xrayMetrics sample + websocket broadcast).
 func (a *ServerController) startTask() {
 	c := global.GetWebServer().GetCron()
-	c.AddFunc("@every 2s", func() {
+	_, _ = c.AddFunc("@every 2s", func() {
 		status := a.serverService.RefreshStatus()
 		if status == nil {
 			return
@@ -97,7 +96,7 @@ func (a *ServerController) startTask() {
 		a.xrayMetricsService.Sample(time.Now())
 		websocket.BroadcastStatus(status)
 	})
-	c.AddFunc("@every 1m", func() {
+	_, _ = c.AddFunc("@every 1m", func() {
 		if err := service.PersistSystemMetrics(); err != nil {
 			logger.Warning("persist system metrics failed:", err)
 		}
@@ -327,13 +326,13 @@ func (a *ServerController) getDb(c *gin.Context) {
 
 	filename := a.serverService.BackupFilename(c.Request.Host)
 	if !filenameRegex.MatchString(filename) {
-		c.AbortWithError(http.StatusBadRequest, fmt.Errorf("invalid filename"))
+		_ = c.AbortWithError(http.StatusBadRequest, fmt.Errorf("invalid filename"))
 		return
 	}
 
 	c.Header("Content-Type", "application/octet-stream")
 	c.Header("Content-Disposition", "attachment; filename="+filename)
-	c.Writer.Write(db)
+	_, _ = c.Writer.Write(db)
 }
 
 // getMigration downloads a cross-engine migration file: a .dump on SQLite or a
@@ -345,13 +344,13 @@ func (a *ServerController) getMigration(c *gin.Context) {
 		return
 	}
 	if !filenameRegex.MatchString(filename) {
-		c.AbortWithError(http.StatusBadRequest, fmt.Errorf("invalid filename"))
+		_ = c.AbortWithError(http.StatusBadRequest, fmt.Errorf("invalid filename"))
 		return
 	}
 
 	c.Header("Content-Type", "application/octet-stream")
 	c.Header("Content-Disposition", "attachment; filename="+filename)
-	c.Writer.Write(data)
+	_, _ = c.Writer.Write(data)
 }
 
 // importDB imports a database file and restarts the Xray service.