feat(browser): add two more flags to text scroll

ts/src/browser.ts

@@ -76,6 +76,8 @@ const EL_FLAGS: Partial<Record<MonoDisplay.ElementTypeName, ElFlagMeta[]>> = {
   HScrollText: [
     { key: "endless",         label: "Endless" },
     { key: "invertDirection", label: "Invert direction" },
+    { key: "padBefore",       label: "Pad Before" },
+    { key: "padAfter",        label: "Pad After" },
   ],
   CurrentTime: [
     { key: "clock12h",    label: "12h mode",      default: false },