Resolve the partner through the shared Tailscale resolver, so a shared-tailnet peer is findable

Plugin/unraid/api/setup.php

@@ -234,11 +234,24 @@ if ($action === 'pull') {
         exit;
     }
 
-    // Resolve HOST1 Tailscale IP
+    // Resolve HOST1's Tailscale IP through the shared resolver, not a bare `tailscale ip -4`.
-    $ip = trim(shell_exec('tailscale ip -4 ' . escapeshellarg($host1Hostname) . ' 2>/dev/null') ?: '');
+    //
+    // master.conf records the OS hostname (unRAID-Gmer4Lfe). Tailscale knows the same machine by
+    // its own name, and when the two nodes are in different tailnets linked by node sharing, a
+    // shared peer is only addressable by its full name — `unraid-gmer4lfe.tonkinese-monster.ts.net`
+    // resolves while both `unRAID-Gmer4Lfe` and `unraid-gmer4lfe` fall through to public DNS and
+    // fail. A bare lookup therefore reported "is Tailscale running on both servers?" on a mesh
+    // where Tailscale was running perfectly on both.
+    //
+    // vv_resolve_tailscale_ip() already handles this: it tries the direct lookup, then falls back
+    // to an unambiguous prefix match against `tailscale status` with the domain stripped, and
+    // refuses to guess when more than one peer could qualify.
+    $ip = vv_resolve_tailscale_ip($host1Hostname);
     if (!$ip) {
         echo json_encode(['ok' => false, 'error' =>
-            "Cannot resolve Tailscale IP for $host1Hostname — is Tailscale running on both servers?"]);
+            "Cannot resolve a Tailscale address for $host1Hostname. Check `tailscale status` on "
+          . "this server — the name in master.conf must match a peer there, or be an unambiguous "
+          . "prefix of one."]);
         exit;
     }