Show status messages on the display

- Clock firmware: 'Connecting to WiFi...' and 'Getting the time...' at
  boot, 'Crashed!' in the OTA-only modes, and 'No WiFi' with the time
  when WiFi is down for over a minute (new DisplayController screen)
- Recovery app: shows its reason, the setup WiFi name, or its IP address,
  then powers the display off (flipdots keep the image)
- StatusScreen and drawTextLines shared by both apps
- Driver: ESP begin() no longer draws 'ESP Connected'
- Tests: No WiFi screen, short reason texts (70 total)

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

src/esp32/logic/boot_policy.cpp

@@ -54,6 +54,24 @@ const char *recoveryReasonText(RecoveryReason reason)
 	}
 }
 
+const char *recoveryReasonShort(RecoveryReason reason)
+{
+	switch (reason)
+	{
+	case RecoveryReason::Wifi:
+		return "no WiFi";
+	case RecoveryReason::Crash:
+		return "crashed";
+	case RecoveryReason::Manual:
+		return "requested";
+	case RecoveryReason::PowerCycle:
+		return "power cycled";
+	case RecoveryReason::None:
+	default:
+		return "no firmware";
+	}
+}
+
 bool powerCyclesRequestRecovery(uint8_t power_on_count)
 {
 	return power_on_count >= POWER_CYCLES_FOR_RECOVERY;

src/esp32/logic/boot_policy.h

@@ -59,6 +59,8 @@ enum class RecoveryReason : uint8_t
 };
 
 const char *recoveryReasonText(RecoveryReason reason);
+// At most 14 characters, for the flipdot display
+const char *recoveryReasonShort(RecoveryReason reason);
 
 // Power-on count: each power on within POWER_CYCLE_WINDOW of the previous one counts.
 // True when the next start should be the recovery app.

src/esp32/logic/display_controller.cpp

@@ -27,8 +27,17 @@ bool DisplayController::powerEnabled() const
 	return _power_enabled;
 }
 
-void DisplayController::update(uint32_t now, bool time_valid, int hour, int minute)
+void DisplayController::update(uint32_t now, bool time_valid, int hour, int minute, bool wifi_connected)
 {
+	if (wifi_connected)
+		_wifi_lost = false;
+	else if (!_wifi_lost)
+	{
+		_wifi_lost = true;
+		_wifi_lost_since = now;
+	}
+	bool show_no_wifi = _wifi_lost && now - _wifi_lost_since >= NO_WIFI_SHOW_TIME;
+
 	// Switched off elsewhere (power timer, Nano flashing): the Nano lost its frame
 	if (!_power.isOn())
 		_screen = Screen::Unknown;
@@ -81,7 +90,7 @@ void DisplayController::update(uint32_t now, bool time_valid, int hour, int minu
 			_power.on();
 			_screen = Screen::Unknown;
 		}
-		_showClock(hour, minute);
+		_showClock(hour, minute, show_no_wifi);
 		break;
 	case ScheduleMode::Standby:
 		// Flipdots keep their image without power, so the last time stays visible
@@ -91,12 +100,16 @@ void DisplayController::update(uint32_t now, bool time_valid, int hour, int minu
 	}
 }
 
-void DisplayController::_showClock(int hour, int minute)
+void DisplayController::_showClock(int hour, int minute, bool no_wifi)
 {
-	if (_screen == Screen::Clock && _shown_hour == hour && _shown_minute == minute)
+	Screen screen = no_wifi ? Screen::NoWifi : Screen::Clock;
+	if (_screen == screen && _shown_hour == hour && _shown_minute == minute)
 		return;
-	_frames.clock(hour, minute);
-	_screen = Screen::Clock;
+	if (no_wifi)
+		_frames.noWifi(hour, minute);
+	else
+		_frames.clock(hour, minute);
+	_screen = screen;
 	_shown_hour = hour;
 	_shown_minute = minute;
 }

src/esp32/logic/display_controller.h

@@ -19,6 +19,8 @@ class Frames
 {
 public:
 	virtual void clock(int hour, int minute) = 0;
+	// Shown instead of the clock while WiFi is down (the time keeps running without it)
+	virtual void noWifi(int hour, int minute) = 0;
 	virtual void logo() = 0;
 	virtual void blank() = 0;
 };
@@ -40,13 +42,15 @@ public:
 	bool powerEnabled() const;
 
 	// Call often (every loop). time_valid is false until the time is synced over NTP.
-	void update(uint32_t now, bool time_valid, int hour, int minute);
+	// While WiFi is down for NO_WIFI_SHOW_TIME, "No WiFi" is shown instead of the clock.
+	void update(uint32_t now, bool time_valid, int hour, int minute, bool wifi_connected);
 
 private:
 	enum class Screen
 	{
 		Unknown, // nothing sent since the last power on
 		Clock,
+		NoWifi,
 		Logo,
 		Blank,
 	};
@@ -62,7 +66,10 @@ private:
 	int _shown_hour = -1;
 	int _shown_minute = -1;
 
-	void _showClock(int hour, int minute);
+	bool _wifi_lost = false;
+	uint32_t _wifi_lost_since = 0;
+
+	void _showClock(int hour, int minute, bool no_wifi);
 	void _showLogo();
 	void _showBlank();
 };