chore(android): companion 0.5.1 (vc21) — refresh served APK + deploy handoff

The APK served from the pairing QR predated today's scanner fixes, so
the download-then-scan flow still hit the laggy scanner. Bumps the
version so phones update in place, refreshes the served artifact
(signed v1+v2+v3, verified), and adds the archi-dev-box deploy handoff.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Android/app/build.gradle.kts

@@ -11,8 +11,8 @@ android {
         applicationId = "com.archipelago.app"
         minSdk = 26
         targetSdk = 35
-        versionCode = 20
-        versionName = "0.5.0"
+        versionCode = 21
+        versionName = "0.5.1"
 
         vectorDrawables {
             useSupportLibrary = true