Add WiFi reconnection retry logic to recover from unreliable WiFi

- Implement periodic WiFi reconnection attempts when stuck in AP mode
- Add WIFI_RECONNECT_INTERVAL_MS config (default 60s) for configurable retry frequency
- Prevent data loss by automatically attempting to switch back to STA mode
- Maintain AP mode for manual configuration if reconnection fails
- Track WiFi config and last reconnection attempt time in shared state
- Add wifi_try_reconnect_sta() and wifi_restore_ap_mode() helper functions
- Log reconnection attempts and results for debugging

include/wifi_manager.h

@@ -25,3 +25,5 @@ bool wifi_connect_sta(const WifiMqttConfig &config, uint32_t timeout_ms = 10000)
 void wifi_start_ap(const char *ap_ssid, const char *ap_pass);
 bool wifi_is_connected();
 String wifi_get_ssid();
+bool wifi_try_reconnect_sta(const WifiMqttConfig &config, uint32_t timeout_ms = 5000);
+void wifi_restore_ap_mode(const char *ap_ssid, const char *ap_pass);