fix: restore service.stop() on explicit Tor OFF for safety

Users in restrictive countries need Tor circuits torn down when they
switch to OFF — an idle proxy still maintains detectable connections.

stop() is now called only on explicit OFF toggle (user action), not on
flow pause/resume (app lifecycle). This avoids file lock races on
resume while ensuring OFF truly disconnects from the Tor network.

https://claude.ai/code/session_01BApgDd5udqBzMqysSRMpZu

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/tor/TorManager.kt

@@ -63,6 +63,7 @@ class TorManager(
                 }
 
                 TorType.OFF -> {
+                    service.stop()
                     emit(TorServiceStatus.Off)
                 }