feat: Go backend, enhanced search, new widgets, Docker deploy

Major changes:
- Add Go backend (backend/) with microservices architecture
- Enhanced master-agents-svc: reranker, content-classifier, stealth-crawler,
  proxy-manager, media-search, fastClassifier, language detection
- New web-svc widgets: KnowledgeCard, ProductCard, ProfileCard, VideoCard,
  UnifiedCard, CardGallery, InlineImageGallery, SourcesPanel, RelatedQuestions
- Improved discover-svc with discover-db integration
- Docker deployment improvements (Caddyfile, vendor.sh, BUILD.md)
- Library-svc: project_id schema migration
- Remove deprecated finance-svc and travel-svc
- Localization improvements across services

Made-with: Cursor

backend/pkg/middleware/logging.go

@@ -0,0 +1,49 @@
+package middleware
+
+import (
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+	"go.uber.org/zap"
+)
+
+type LoggingConfig struct {
+	Logger    *zap.Logger
+	SkipPaths []string
+}
+
+func Logging(config LoggingConfig) fiber.Handler {
+	logger := config.Logger
+	if logger == nil {
+		logger, _ = zap.NewProduction()
+	}
+
+	skipPaths := make(map[string]bool)
+	for _, path := range config.SkipPaths {
+		skipPaths[path] = true
+	}
+
+	return func(c *fiber.Ctx) error {
+		path := c.Path()
+		if skipPaths[path] {
+			return c.Next()
+		}
+
+		start := time.Now()
+
+		err := c.Next()
+
+		duration := time.Since(start)
+
+		logger.Info("request",
+			zap.String("method", c.Method()),
+			zap.String("path", path),
+			zap.Int("status", c.Response().StatusCode()),
+			zap.Duration("latency", duration),
+			zap.String("ip", c.IP()),
+			zap.String("user-agent", c.Get("User-Agent")),
+		)
+
+		return err
+	}
+}