M1 step 2: Wi-Fi Service, Saved Networks, NTP, Settings page

- lib/wifi (host-tested): SavedNetworks (up to 8, validated, hidden
  flag, persisted) and WifiController (joins the strongest Saved
  Network, tries hidden ones in turn, backoff 10/30/60 s, connect
  timeout, Monitoring override, radio off without Saved Networks)
- WifiService carries out the controller's actions, sets the EU
  country code, and syncs the Clock over SNTP without touching the TZ
- Wi-Fi On/Off setting; Settings > Wi-Fi page: status, add from a scan
  or a hidden network, forget
- Status Bar: W + signal bars, W? while searching, MON while monitoring
- Serial: wifi add / wifi status (replaces the step 1 heap probe)

Verified on the device: joins the test network ~5 s after boot, clock
set over NTP, ~129 KB free heap while connected.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/apps/wifi_settings_page.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <memory>
+#include <string>
+
+#include "dialog_model.h"
+#include "event_bus.h"
+#include "key_event.h"
+#include "line_editor.h"
+#include "list_model.h"
+#include "saved_networks.h"
+#include "services/wifi_service.h"
+#include "settings.h"
+#include "ui/canvas.h"
+#include "ui/theme.h"
+
+namespace roro {
+
+// Settings → Wi-Fi: the On/Off switch, current connection, Saved Networks, and adding networks
+// from a scan or by name (hidden). Owned by the Settings App.
+class WifiSettingsPage {
+   public:
+    WifiSettingsPage(Settings& settings, SavedNetworks& saved, WifiService& wifi, EventBus& bus)
+        : settings_(settings), saved_(saved), wifi_(wifi), bus_(bus) {}
+
+    void enter();
+    bool onKey(const KeyEvent& e);  // false: leave the page
+    bool textEntryActive() const { return view_ == View::Ssid || view_ == View::Password; }
+    bool live() const { return view_ == View::Main || view_ == View::Scan; }  // redraw periodically
+    void draw(Canvas& c);
+
+   private:
+    enum class View { Main, Scan, Ssid, Password };
+    enum Fixed { kToggle, kStatus, kAddScanned, kAddHidden, kFixedRows };
+
+    void refreshMain();
+    void warn(const std::string& text, NotificationLevel level = NotificationLevel::Warning);
+    std::string statusText() const;
+
+    Settings& settings_;
+    SavedNetworks& saved_;
+    WifiService& wifi_;
+    EventBus& bus_;
+    View view_ = View::Main;
+    ListModel main_{theme::kContent.h / theme::kLineHeight};
+    ListModel scan_{theme::kContent.h / theme::kLineHeight};
+    LineEditor editor_{63};
+    std::string newSsid_;
+    bool newHidden_ = false;
+    std::unique_ptr<DialogModel> forgetDialog_;
+};
+
+}  // namespace roro