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/settings_app.h

@@ -13,6 +13,7 @@
 #include "services/battery_service.h"
 #include "services/clock_service.h"
 #include "services/storage_service.h"
+#include "apps/wifi_settings_page.h"
 #include "settings_menu.h"
 #include "ui/theme.h"
 
@@ -25,20 +26,25 @@ struct SettingsAppDeps {
     BatteryService& battery;
     StorageService& storage;
     ClockService& clock;
+    WifiService& wifi;
+    SavedNetworks& savedNetworks;
 };
 
 // Settings: every user-facing setting, plus the Storage and About pages.
 class SettingsApp : public App {
    public:
-    explicit SettingsApp(const SettingsAppDeps& deps) : d_(deps), menu_(deps.settings) {}
+    explicit SettingsApp(const SettingsAppDeps& deps)
+        : d_(deps), menu_(deps.settings), wifiPage_(deps.settings, deps.savedNetworks, deps.wifi, deps.bus) {}
     void onEnter() override;
     bool onKey(const KeyEvent& e) override;
     void update(uint32_t nowMs) override;
-    bool textEntryActive() const override { return page_ == Page::Text; }
+    bool textEntryActive() const override {
+        return page_ == Page::Text || (page_ == Page::Wifi && wifiPage_.textEntryActive());
+    }
     void draw(Canvas& c) override;
 
    private:
-    enum class Page { Menu, Text, Choice, Storage, About };
+    enum class Page { Menu, Text, Choice, Storage, About, Wifi };
 
     bool onMenuKey(const KeyEvent& e);
     bool onTextKey(const KeyEvent& e);
@@ -51,6 +57,7 @@ class SettingsApp : public App {
 
     SettingsAppDeps d_;
     SettingsMenu menu_;
+    WifiSettingsPage wifiPage_;
     Page page_ = Page::Menu;
     ListModel list_{theme::kContent.h / theme::kLineHeight};
     ListModel choices_{theme::kContent.h / theme::kLineHeight};