feat(route): trace per link, to the node or the last repeater, find where it stops; channel order re-sorts on entry

Core: PathEditor results are links (node k hearing k-1 and back); toNode()
off traces only the repeaters (a companion answers only with repeat on);
probe() traces to each repeater in turn after no reply; failures carry a
reason; an empty list saves "direct". PingEngine takes over a slot left past
its timeout. A kept route: the dropped heard path isn't announced to the app
nor bumps lastmod; an app update keeps the flag only if it leaves the route.
Marker boxes sized for every dot and name (overflow).

ui-lvgl Route: one line per node with out / back dB coloured by quality, tap
a hop to move / remove, tap the node to include it, Keep in the header, Find
where beside a no-reply status. ui-new Path: To node / Find break rows,
result alerts, cursor kept on its action.

Channels: ui-new re-sorts the list on entering it, cursor on the same channel.
Docs: Path and trace, Channel order. Sim hooks: open route, add channel,
open messages.

Checked in the browser sim (L2 + ui-new peer + repeater); not on hardware.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-lvgl/MapScreen.h

@@ -874,9 +874,9 @@ void UITask::layoutMapMarks(double left, double top, int w, int h) {
   const int half = MARK_D / 2;
   const int lh = lv_font_get_line_height(THEME_FONT_SMALL) + 2;
   struct Box { int16_t x1, y1, x2, y2; };
-  static Box used[MAX_MARKS + 8];
+  static Box used[6 + MAX_MARKS + MARK_LABELS_MAX];   // the map's controls, the dots, the names
   int nu = 0;
-  const int bottom = _map_nav ? navmap::BAR_H : 0;
+  const int bottom = _map_nav || _route_pick ? navmap::BAR_H : 0;   // the nav bar, or the route's
   const int16_t W = (int16_t)w, H = (int16_t)(h - bottom);
   used[nu++] = { 0, 0, 50, 144 };                                      // button columns
   used[nu++] = { (int16_t)(W - 50), 0, W, 144 };