Network Connection Logic Enhancement

Nucleic-Session: 93A70648-2057-4092-9372-860E1BA151D8
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Models/HostConnection.swift

@@ -820,3 +820,17 @@ final class HostConnection {
         client = nil
     }
 }
+
+/// A thread-safe "fire once" latch: the `NWConnection` reachability probe resolves its continuation
+/// from a state callback *or* a timeout, on the same queue but from different closures — `take()`
+/// returns true to exactly one caller so the continuation is resumed exactly once.
+private final class ProbeOnce: @unchecked Sendable {
+    private let lock = NSLock()
+    private var done = false
+    func take() -> Bool {
+        lock.lock(); defer { lock.unlock() }
+        if done { return false }
+        done = true
+        return true
+    }
+}