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/auth.go

@@ -0,0 +1,50 @@
+package middleware
+
+import (
+	"strings"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+type AuthConfig struct {
+	RequireAuth bool
+	SkipPaths   []string
+}
+
+func Auth(config AuthConfig) fiber.Handler {
+	return func(c *fiber.Ctx) error {
+		if !config.RequireAuth {
+			return c.Next()
+		}
+
+		path := c.Path()
+		for _, skip := range config.SkipPaths {
+			if strings.HasPrefix(path, skip) {
+				return c.Next()
+			}
+		}
+
+		auth := c.Get("Authorization")
+		if auth == "" {
+			return c.Status(401).JSON(fiber.Map{
+				"error": "Unauthorized",
+			})
+		}
+
+		if !strings.HasPrefix(auth, "Bearer ") {
+			return c.Status(401).JSON(fiber.Map{
+				"error": "Invalid authorization format",
+			})
+		}
+
+		return c.Next()
+	}
+}
+
+func ExtractToken(c *fiber.Ctx) string {
+	auth := c.Get("Authorization")
+	if strings.HasPrefix(auth, "Bearer ") {
+		return strings.TrimPrefix(auth, "Bearer ")
+	}
+	return ""
+}