feat(ux): wizard handoff note, daemon restart reminder, settings polish (code)

The code changes intended with the settings_window removal in a90aa29 (a bad
git-add pathspec aborted staging them there, leaving that commit with only the
file deletions and CMakeLists still referencing them):
- First-run handoff info toast at the completion point.
- Daemon-updater "restart pending" reminder (Settings → Daemon Binary) + the
  Done screen's warning-level "restart required" headline.
- Debug restart-note raised to a readable color with the restart prompt beneath
  it; DEBUG OPTIONS header shows a lock + explanatory caption (auth gate
  unchanged); a few hardcoded literals → material tokens / dpiScale.
- Drop the legacy settings_window from the build (CMakeLists + the dev-only
  references) to match the file deletions.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app.h

@@ -769,6 +769,9 @@ public:
      * Shows "Restarting daemon..." in the loading overlay while the daemon cycles.
      */
     void restartDaemon();
+    // A newer daemon binary is installed but the running node is still the old one until a restart.
+    void markDaemonRestartPending() { daemon_restart_pending_.store(true); }
+    bool daemonRestartPending() const { return daemon_restart_pending_.load(); }
     // Switch the active wallet: persist the new -wallet=<name>, stop the node, restart on it
     // (rescan only if it was never synced in this datadir). Per-wallet data follows automatically
     // via the identity-scoped caches (P1). No-op if that wallet is already active.
@@ -1311,6 +1314,7 @@ private:
 
     // Daemon restart (e.g. after changing debug log categories)
     std::atomic<bool> daemon_restarting_{false};
+    std::atomic<bool> daemon_restart_pending_{false};  // updated binary installed, awaiting a restart
 
     // Wallet-switch failure recovery: the switch worker sets wallet_switch_failed_ when the new
     // wallet's daemon won't start/stay up; the main loop then reverts active_wallet_file to
@@ -1401,7 +1405,6 @@ private:
     // UI State
     bool quit_requested_ = false;
     bool show_demo_window_ = false;
-    bool show_settings_ = false;
     bool show_about_ = false;
     bool show_faq_ = false;
     bool show_import_key_ = false;