Refuse to join the pair, rather than undoing it a second later

Connecting both pods is the configuration in which the `−` pod stops
reporting its own paddle (§2.3.1). `Cmd::Seen` has always known that and
declined; an explicit `Cmd::Connect` walked straight past it, and
housekeeping then closed the redundant link a second or so later — which
looks like the app handling the case and is not the same thing. On the
tablet, 2026-08-27 15:55:39, the pair was joined for 1.4 s and the `−`
pod did not report another press for the rest of the session, across two
fresh links and an app reinstall.

So the rule now lives on both paths. `auto` is still armed by the refused
request, so the fallback stands: the moment the `−` pod goes away, the
`+` pod is taken on its next advertisement.

And the UI stops offering the trap. The `+` pod's "Connect anyway" sat
next to a working controller, which put the one action that breaks
shifting a single tap from a rider hunting for a way to fix shifting. It
now reads "Held in reserve", which is what that pod is.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "BikeControl",
-  "version": "0.2.4",
+  "version": "0.2.5",
   "identifier": "paris.tourolle.bikecontrol",
   "build": {
     "frontendDist": "../ui/dist",
@@ -43,7 +43,7 @@
     ],
     "category": "Utility",
     "android": {
-      "versionCode": 1204
+      "versionCode": 1205
     },
     "shortDescription": "Indoor cycling trainer control",
     "longDescription": "Control a smart trainer over BLE, ride gradient profiles and synthetic waveforms, and record the result."