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/config/settings.h

@@ -201,6 +201,10 @@ public:
 
     bool getUseTor() const { return use_tor_; }
     void setUseTor(bool tor) { use_tor_ = tor; }
+    // "Use Tor" was never implemented: no build routed any traffic through Tor. Clears a stored opt-in
+    // and reports whether there was one, so App::init can tell that user once (the cleared key is the
+    // "already told" flag).
+    bool consumeLegacyUseTor() { const bool was = use_tor_; use_tor_ = false; return was; }
 
     // Fees
     bool getAllowCustomFees() const { return allow_custom_fees_; }