Docs: update according to changes in the new versions

web-panel.md:
- Replace Start OTA nav item with dedicated Firmware Update section
- Update Info panel: Version/Client Version → Hardware/Firmware
- Add auto-refresh toggle to /stats element list
- Expand Trends list: add error_rate, core0_util, mcu_temp,
  note RX/TX stacked rendering of packets series
- Update sequential trend loading order accordingly
- Rewrite OTA subsection to describe native HTTPS upload flow

api.md:
- Add error_rate and core0_util to supported series list

boards.md:
- Add DIY_ESP32S3_N16R8_E22_Back2back to repeater_mqtt table

local-builds.md:
- Add DIY_ESP32S3_N16R8_E22_Back2back_repeater_mqtt
- Add Ebyte_EoRa-S3_Repeater_mqtt
- Add ThinkNode_M2_Repeater_mqtt
- Add ThinkNode_M5_Repeater_mqtt

docs/api.md

@@ -166,6 +166,8 @@ curl -sk https://<repeater-ip>/api/stats \
 - `signal`
 - `noise_floor`
 - `packets`
+- `error_rate`
+- `core0_util`
 - `voltage`
 - `sensor_temp`
 - `humidity`