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",