Use TorManager's socksPort when checking proxy liveness for built-in Tor

Expose the actual SOCKS port assigned by kmp-tor as TorManager.socksPort
(StateFlow<Int>, 0 when not running). isSocksProxyAlive now connects to
that port instead of unconditionally returning isRunning, giving a real
liveness check. Also clears _socksPort to 0 on stop.

https://claude.ai/code/session_01JwcwxdYrDnr3QyHqTBz33a

app/src/free/java/com/greenart7c3/nostrsigner/service/TorManager.kt

@@ -45,6 +45,9 @@ object TorManager {
     private val _isRunning = MutableStateFlow(false)
     val isRunning: StateFlow<Boolean> = _isRunning.asStateFlow()
 
+    private val _socksPort = MutableStateFlow(0)
+    val socksPort: StateFlow<Int> = _socksPort.asStateFlow()
+
     fun init(context: Context) {
         if (appContext != null) return
         appContext = context.applicationContext
@@ -122,6 +125,7 @@ object TorManager {
                             try {
                                 val port = addr.port.value
                                 Log.i(TAG, "Built-in Tor SOCKS proxy on port $port")
+                                _socksPort.value = port
                                 HttpClientManager.setDefaultProxyOnPort(port)
                                 _isRunning.value = true
                                 appContext?.let { showNotification(it.getString(R.string.builtin_tor_active)) }
@@ -151,6 +155,7 @@ object TorManager {
         val runtime = torRuntime ?: return
         torRuntime = null
         _isRunning.value = false
+        _socksPort.value = 0
         cancelNotification()
         try {
             runBlocking(Dispatchers.IO) { runtime.stopDaemonAsync() }

app/src/main/java/com/greenart7c3/nostrsigner/Amber.kt

@@ -143,7 +143,16 @@ class Amber :
 
     fun isSocksProxyAlive(proxyHost: String, proxyPort: Int): Boolean {
         if (settings.torMode == TorMode.BUILTIN) {
-            return TorManager.isRunning.value
+            val port = TorManager.socksPort.value
+            if (port == 0) return false
+            return try {
+                val socket = Socket()
+                socket.connect(InetSocketAddress(proxyHost, port), 5000)
+                socket.close()
+                true
+            } catch (e: Exception) {
+                false
+            }
         }
         try {
             val socket = Socket()