feat(route): Discover - path discovery from the device, 1/3/5 tries 20 s apart, the routes found to use in the route editor

MyMesh::sendPathDiscovery() shares the request with the app's
CMD_SEND_PATH_DISCOVERY_REQ and hands the reply (the way there and back)
to the UI; PathEditor keeps up to 4 distinct routes with how often each
came. L2: Find the route under Route; L1: Discover row in Path / trace.
Docs: Discover, message routes on the map, Ask status and discovery.

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

docs/solo/settings.md

@@ -68,7 +68,10 @@ nodes aren't added until you make room.
   **Allowed** (the contacts you gave that permission: **Telem** in a node's
   options in [Nodes](./contacts.md#nearby-nodes), or the phone app) or
   **Everyone**. Status is the battery; a request for location or
-  sensors is answered only where status is allowed too.
+  sensors is answered only where status is allowed too. Status also lets
+  others find a route to you (**Discover** in
+  [Path and trace](./contacts.md#path-and-trace), or the phone app's path
+  discovery).
 - **BT PIN**: the six-digit Bluetooth pairing PIN. Leave it empty for a new
   random one at each start, shown on screen. A new PIN is used from the next
   start; the phone pairs again after that.