Add Radar DC Telegram functionality and configuration

- Introduced new `RadarConfig` structure in `config.go` to manage radar settings, including `statuses_url`, `http_timeout_ms`, and `ping_from`.
- Implemented validation for radar configuration in `config_test.go` to ensure correct URL schemes and timeout limits.
- Added new API routes for radar statuses and ping functionality in the gateway, enhancing the service's capabilities.
- Updated documentation in `GATEWAY_RUN.md` to include details about the new radar features and their usage.
- Enhanced the user interface to include navigation and display options for the Radar DC section in the sidebar and page titles.
- Added client-side API functions for fetching radar statuses and ping responses, improving integration with the frontend.

internal/server/radar_test.go

@@ -0,0 +1,19 @@
+package server
+
+import "testing"
+
+func TestHostOnly(t *testing.T) {
+	tests := []struct {
+		in, want string
+	}{
+		{"example.com:8080", "example.com"},
+		{"[::1]:443", "::1"},
+		{"127.0.0.1", "127.0.0.1"},
+		{"", ""},
+	}
+	for _, tt := range tests {
+		if got := hostOnly(tt.in); got != tt.want {
+			t.Errorf("hostOnly(%q) = %q, want %q", tt.in, got, tt.want)
+		}
+	}
+}