fix: resolve all linting and formatting issues

- Fix error return value checks (errcheck)
- Fix unused parameters by using underscore prefix
- Add missing package comments to all packages
- Fix context key type issue in middleware (use typed contextKey)
- Replace deprecated trace.NewNoopTracerProvider with noop.NewTracerProvider
- Fix embedded field selector in database client
- Remove trailing whitespace
- Remove revive linter (as requested) to avoid stuttering warnings for public API interfaces

All linting and formatting checks now pass.

internal/di/providers.go

@@ -19,6 +19,7 @@ import (
 	"git.dcentral.systems/toolz/goplt/pkg/errorbus"
 	"git.dcentral.systems/toolz/goplt/pkg/logger"
 	"go.opentelemetry.io/otel/trace"
+	"go.opentelemetry.io/otel/trace/noop"
 	"go.uber.org/fx"
 )
 
@@ -130,7 +131,7 @@ func ProvideDatabase() fx.Option {
 				log.Info("Database migrations completed successfully")
 				return nil
 			},
-			OnStop: func(ctx context.Context) error {
+			OnStop: func(_ context.Context) error {
 				return dbClient.Close()
 			},
 		})
@@ -147,7 +148,7 @@ func ProvideErrorBus() fx.Option {
 
 		// Register lifecycle hook to close the bus on shutdown
 		lc.Append(fx.Hook{
-			OnStop: func(ctx context.Context) error {
+			OnStop: func(_ context.Context) error {
 				return bus.Close()
 			},
 		})
@@ -181,7 +182,7 @@ func ProvideTracer() fx.Option {
 		enabled := cfg.GetBool("tracing.enabled")
 		if !enabled {
 			// Return no-op tracer
-			return trace.NewNoopTracerProvider(), nil
+			return noop.NewTracerProvider(), nil
 		}
 
 		serviceName := cfg.GetString("tracing.service_name")
@@ -248,8 +249,7 @@ func ProvideHTTPServer() fx.Option {
 
 		// Register lifecycle hooks
 		lc.Append(fx.Hook{
-			OnStart: func(ctx context.Context) error {
-
+			OnStart: func(_ context.Context) error {
 				// Get server address from config
 				port := cfg.GetInt("server.port")
 				if port == 0 {
@@ -300,7 +300,7 @@ func ProvideHTTPServer() fx.Option {
 						)
 						// Continue anyway - server might still be starting
 					} else {
-						resp.Body.Close()
+						_ = resp.Body.Close()
 					}
 
 					log.Info("HTTP server started successfully",

internal/ent/schema/audit_log.go

@@ -1,3 +1,4 @@
+// Package schema defines the Ent schema for domain entities.
 package schema
 
 import (
@@ -46,4 +47,3 @@ func (AuditLog) Indexes() []ent.Index {
 		index.Fields("action"),
 	}
 }
-

internal/ent/schema/permission.go

@@ -30,4 +30,3 @@ func (Permission) Edges() []ent.Edge {
 		edge.To("role_permissions", RolePermission.Type),
 	}
 }
-

internal/ent/schema/role.go

@@ -37,4 +37,3 @@ func (Role) Edges() []ent.Edge {
 		edge.To("user_roles", UserRole.Type),
 	}
 }
-

internal/ent/schema/role_permission.go

@@ -32,4 +32,3 @@ func (RolePermission) Edges() []ent.Edge {
 			Field("permission_id"),
 	}
 }
-

internal/ent/schema/user.go

@@ -41,4 +41,3 @@ func (User) Edges() []ent.Edge {
 		edge.To("user_roles", UserRole.Type),
 	}
 }
-

internal/ent/schema/user_role.go

@@ -32,4 +32,3 @@ func (UserRole) Edges() []ent.Edge {
 			Field("role_id"),
 	}
 }
-

internal/errorbus/channel_bus.go

@@ -1,3 +1,4 @@
+// Package errorbus provides a channel-based error bus implementation.
 package errorbus
 
 import (
@@ -11,17 +12,17 @@ import (
 
 // ChannelBus implements a channel-based error bus.
 type ChannelBus struct {
-	errors    chan errorWithContext
-	logger    logger.Logger
-	done      chan struct{}
-	wg        sync.WaitGroup
-	once      sync.Once
+	errors chan errorWithContext
+	logger logger.Logger
+	done   chan struct{}
+	wg     sync.WaitGroup
+	once   sync.Once
 }
 
 type errorWithContext struct {
-	err     error
-	ctx     context.Context
-	stack   []byte
+	err   error
+	ctx   context.Context
+	stack []byte
 }
 
 // NewChannelBus creates a new channel-based error bus.
@@ -162,4 +163,3 @@ func (b *ChannelBus) Close() error {
 
 // Ensure ChannelBus implements ErrorPublisher
 var _ errorbus.ErrorPublisher = (*ChannelBus)(nil)
-

internal/health/database.go

@@ -1,3 +1,4 @@
+// Package health provides health check implementations for various components.
 package health
 
 import (
@@ -23,4 +24,3 @@ func NewDatabaseChecker(client *database.Client) health.HealthChecker {
 func (d *DatabaseChecker) Check(ctx context.Context) error {
 	return d.client.Ping(ctx)
 }
-

internal/health/registry.go

@@ -60,7 +60,7 @@ func (r *Registry) Check(ctx context.Context) health.HealthStatus {
 }
 
 // LivenessCheck performs a basic liveness check (no dependencies).
-func (r *Registry) LivenessCheck(ctx context.Context) health.HealthStatus {
+func (r *Registry) LivenessCheck(_ context.Context) health.HealthStatus {
 	// Liveness is always healthy if the service is running
 	return health.HealthStatus{
 		Status: health.StatusHealthy,
@@ -71,4 +71,3 @@ func (r *Registry) LivenessCheck(ctx context.Context) health.HealthStatus {
 func (r *Registry) ReadinessCheck(ctx context.Context) health.HealthStatus {
 	return r.Check(ctx)
 }
-

internal/infra/database/client.go

@@ -1,3 +1,4 @@
+// Package database provides database client and connection management.
 package database
 
 import (
@@ -20,11 +21,11 @@ type Client struct {
 
 // Config holds database configuration.
 type Config struct {
-	DSN              string
-	MaxConnections   int
-	MaxIdleConns     int
-	ConnMaxLifetime  time.Duration
-	ConnMaxIdleTime  time.Duration
+	DSN             string
+	MaxConnections  int
+	MaxIdleConns    int
+	ConnMaxLifetime time.Duration
+	ConnMaxIdleTime time.Duration
 }
 
 // NewClient creates a new Ent client with connection pooling.
@@ -46,7 +47,7 @@ func NewClient(cfg Config) (*Client, error) {
 	defer cancel()
 
 	if err := db.PingContext(ctx); err != nil {
-		db.Close()
+		_ = db.Close()
 		return nil, fmt.Errorf("failed to ping database: %w", err)
 	}
 
@@ -72,7 +73,7 @@ func (c *Client) Close() error {
 
 // Migrate runs database migrations.
 func (c *Client) Migrate(ctx context.Context) error {
-	return c.Client.Schema.Create(ctx)
+	return c.Schema.Create(ctx)
 }
 
 // Ping checks database connectivity.
@@ -84,4 +85,3 @@ func (c *Client) Ping(ctx context.Context) error {
 func (c *Client) DB() *sql.DB {
 	return c.db
 }
-

internal/metrics/metrics.go

@@ -1,3 +1,4 @@
+// Package metrics provides Prometheus metrics collection and instrumentation.
 package metrics
 
 import (
@@ -12,9 +13,9 @@ import (
 // Metrics holds all Prometheus metrics.
 type Metrics struct {
 	httpRequestDuration *prometheus.HistogramVec
-	httpRequestTotal   *prometheus.CounterVec
-	httpErrorsTotal    *prometheus.CounterVec
-	registry           *prometheus.Registry
+	httpRequestTotal    *prometheus.CounterVec
+	httpErrorsTotal     *prometheus.CounterVec
+	registry            *prometheus.Registry
 }
 
 // NewMetrics creates a new metrics registry with all metrics.
@@ -94,4 +95,3 @@ func (m *Metrics) Handler() http.Handler {
 func (m *Metrics) Registry() *prometheus.Registry {
 	return m.registry
 }
-

internal/observability/tracer.go

@@ -1,3 +1,4 @@
+// Package observability provides OpenTelemetry tracing setup and configuration.
 package observability
 
 import (
@@ -13,22 +14,23 @@ import (
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
 	"go.opentelemetry.io/otel/trace"
+	"go.opentelemetry.io/otel/trace/noop"
 )
 
 // Config holds OpenTelemetry configuration.
 type Config struct {
-	Enabled      bool
-	ServiceName  string
+	Enabled        bool
+	ServiceName    string
 	ServiceVersion string
-	Environment  string
-	OTLPEndpoint string
+	Environment    string
+	OTLPEndpoint   string
 }
 
 // InitTracer initializes OpenTelemetry tracing.
 func InitTracer(ctx context.Context, cfg Config) (trace.TracerProvider, error) {
 	if !cfg.Enabled {
 		// Return a no-op tracer provider
-		return trace.NewNoopTracerProvider(), nil
+		return noop.NewTracerProvider(), nil
 	}
 
 	// Create resource with service information
@@ -91,4 +93,3 @@ func ShutdownTracer(ctx context.Context, tp trace.TracerProvider) error {
 	}
 	return nil
 }
-

internal/server/middleware.go

@@ -1,3 +1,4 @@
+// Package server provides HTTP middleware functions for request processing.
 package server
 
 import (
@@ -6,15 +7,17 @@ import (
 	"runtime"
 	"time"
 
-	"github.com/gin-gonic/gin"
-	"github.com/google/uuid"
 	"git.dcentral.systems/toolz/goplt/pkg/errorbus"
 	"git.dcentral.systems/toolz/goplt/pkg/logger"
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
 )
 
+type contextKey string
+
 const (
-	requestIDKey = "request_id"
-	userIDKey    = "user_id"
+	requestIDKey contextKey = "request_id"
+	userIDKey    contextKey = "user_id"
 )
 
 // RequestIDMiddleware generates a unique request ID for each request.
@@ -25,7 +28,7 @@ func RequestIDMiddleware() gin.HandlerFunc {
 			requestID = uuid.New().String()
 		}
 
-		c.Set(requestIDKey, requestID)
+		c.Set(string(requestIDKey), requestID)
 		c.Header("X-Request-ID", requestID)
 		c.Next()
 	}
@@ -45,7 +48,7 @@ func LoggingMiddleware(log logger.Logger) gin.HandlerFunc {
 		duration := time.Since(start)
 
 		// Get request ID from context
-		requestID, _ := c.Get(requestIDKey)
+		requestID, _ := c.Get(string(requestIDKey))
 		requestIDStr := ""
 		if id, ok := requestID.(string); ok {
 			requestIDStr = id
@@ -74,8 +77,8 @@ func PanicRecoveryMiddleware(errorBus errorbus.ErrorPublisher) gin.HandlerFunc {
 				stack = stack[:n]
 
 				// Get request ID from context
-				requestID, _ := c.Get(requestIDKey)
-				ctx := context.WithValue(context.Background(), "request_id", requestID)
+				requestID, _ := c.Get(string(requestIDKey))
+				ctx := context.WithValue(context.Background(), requestIDKey, requestID)
 
 				// Create error
 				var panicErr error
@@ -138,4 +141,3 @@ func TimeoutMiddleware(timeout time.Duration) gin.HandlerFunc {
 		c.Next()
 	}
 }
-