fix(settings): disable the unimplemented Tor option and tell its users

The "Use Tor" checkbox was saved but never read: no build routed any
traffic (node, RPC, price/update/bootstrap/pool HTTP or Lite gRPC)
through Tor, so users who ticked it believed they were anonymous.

- The checkbox is disabled and always shown unticked, on the Settings
  page and in the legacy Settings window. Its tooltip says it is not
  available and gives the alternatives: for the node, proxy=127.0.0.1:9050
  in DRAGONX.conf with Tor running; otherwise a system-wide VPN/Tor (Lite
  builds get the short version). The "Use Tor" label is kept.
- Behaviour change: a stored use_tor=true is cleared once at startup
  (Settings::consumeLegacyUseTor + a synchronous save before the async
  writer and any Settings page state), with a 20 s warning in the user's
  language. The cleared key is the "already told" flag, so the notice
  never repeats. No settings format change.
- 3 new strings (tt_tor_unavailable, tt_tor_unavailable_lite,
  tor_never_applied_notice) in all 8 languages; the tooltip wraps at
  tor-tooltip-wrap-width from ui.toml.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app.cpp

@@ -412,6 +412,14 @@ bool App::init()
         settings_->save();   // no writer attached yet: synchronous
         settings_->clearUpgradeSave();
     }
+    // "Use Tor" never did anything. Clear a stored opt-in once, synchronously and before any Settings
+    // page state is loaded (so nothing writes it back), and warn that user below, once the saved
+    // language is loaded.
+    const bool legacyTorCleared = settings_->consumeLegacyUseTor();
+    if (legacyTorCleared) {
+        DEBUG_LOGF("[INFO] Cleared the unimplemented use_tor setting\n");
+        settings_->save();   // no writer attached yet: synchronous
+    }
     // From here on settings_->save() is written by file_writer_ off the UI thread (flushed by main()
     // at exit); a save after a fund/security-critical setter still waits for the disk (Settings::save).
     settings_->setFileWriter(&file_writer_);
@@ -501,6 +509,8 @@ bool App::init()
     if (!lang.empty()) {
         util::I18n::instance().loadLanguage(lang);
     }
+    if (legacyTorCleared)
+        ui::Notifications::instance().warning(TR("tor_never_applied_notice"), 20.0f);
 
     // Initialize RPC client
     rpc_ = std::make_unique<rpc::RPCClient>();