v1.0.14: Display blanking config in captive portal

- Add Options section to captive portal with display blanking dropdown
- Options: Never, 1, 5, 10, 30, 60 minutes
- Change EEPROM blanking value from seconds to minutes (supports up to 255 min)
- Update Display.h and Utilities.h to interpret stored value as minutes
- Default blanking timeout changed from 15s to 1 minute

Utilities.h

@@ -1789,12 +1789,13 @@ void da_conf_save(uint8_t dadr) {
 }
 
 void db_conf_save(uint8_t val) {
+	// val is in minutes (0 = disabled)
 	#if HAS_DISPLAY
 		if (val == 0x00) {
 			display_blanking_enabled = false;
 		} else {
 			display_blanking_enabled = true;
-			display_blanking_timeout = val*1000;
+			display_blanking_timeout = (uint32_t)val * 60UL * 1000UL;
 		}
 		eeprom_update(eeprom_addr(ADDR_CONF_BSET), CONF_OK_BYTE);
 		eeprom_update(eeprom_addr(ADDR_CONF_DBLK), val);