fix(companion): mesh VPN no longer blocks IPv4 + off-LAN connect via mesh ULA

Field test on 5G (Framework PT): pairing scanned fine but connect
hard-failed on the scanned LAN IP, and enabling the mesh VPN killed the
phone's internet.

- ArchyVpnService: the TUN is IPv6-only, and Android blocks every
  address family the VPN holds no address for — allowFamily(AF_INET)
  (+ allowBypass) so normal traffic flows while only fd00::/8 is routed.
- ServerConnectScreen.connect(): when the LAN address doesn't answer and
  the entry carries a mesh ULA, bring the tunnel up (autoStartIfReady)
  and probe the ULA with retries before reporting failure — the scanned
  IP is a dial hint, the npub/ULA is the identity (npub-first contract).
- Served companion APK refreshed as 0.5.2 (vc22); handoff doc updated.

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 = 21
-        versionName = "0.5.1"
+        versionCode = 22
+        versionName = "0.5.2"
 
         vectorDrawables {
             useSupportLibrary = true