Fix OTA update for C3 from 0.15 (#5072)

* change C3 to DIO, add explicit QIO env for C3, add markOTAvalid() to support OTA from 0.15

platformio.ini

@@ -25,6 +25,7 @@ default_envs = nodemcuv2
                esp32_wrover
                lolin_s2_mini
                esp32c3dev
+               esp32c3dev_qio
                esp32s3dev_16MB_opi
                esp32s3dev_8MB_opi
                esp32s3_4M_qspi
@@ -543,6 +544,12 @@ build_flags = ${common.build_flags} ${esp32c3.build_flags} -D WLED_RELEASE_NAME=
 upload_speed = 460800
 build_unflags = ${common.build_unflags}
 lib_deps = ${esp32c3.lib_deps}
+board_build.flash_mode = dio ; safe default, required for OTA updates to 0.16 from older version which used dio (must match the bootloader!)
+
+[env:esp32c3dev_qio]
+extends = env:esp32c3dev
+build_flags = ${common.build_flags} ${esp32c3.build_flags} -D WLED_RELEASE_NAME=\"ESP32-C3-QIO\"
+board_build.flash_mode = qio ; qio is faster and works on almost all boards (some boards may use dio to get 2 extra pins)
 
 [env:esp32s3dev_16MB_opi]
 ;; ESP32-S3 development board, with 16MB FLASH and >= 8MB PSRAM (memory_type: qio_opi)