Add navbar and home page with search functionality

- Create new home page (/) with overview stats, ASN lookup,
  AS name search, and IP address lookup with JSON display
- Add responsive navbar to all pages with app branding
- Navbar shows "routewatch by @sneak" with link to author
- Status page accessible via navbar link
- Remove redirect from / to /status, serve home page instead

internal/server/routes.go

@@ -21,7 +21,7 @@ func (s *Server) setupRoutes() {
 	r.Use(JSONResponseMiddleware)
 
 	// Routes
-	r.Get("/", s.handleRoot())
+	r.Get("/", s.handleIndex())
 	r.Get("/status", s.handleStatusHTML())
 	r.Get("/status.json", JSONValidationMiddleware(s.handleStatusJSON()).ServeHTTP)
 	r.Get("/.well-known/healthcheck.json", JSONValidationMiddleware(s.handleHealthCheck()).ServeHTTP)