fix(boards): Elecrow ThinkNode-M2 uses CH340K, not CP2102

The shipping revision of this board has a WCH CH340K USB-UART bridge
(1a86:7522), not a Silicon Labs CP2102 as the original board-module
comment claimed. Update the doc header, and add the CH340K +
CH340-standard VID:PIDs to the `just flash` port list so we stop
falling through to espflash auto-detect on these boards.

justfile

@@ -77,7 +77,7 @@ flash board:
     @read -r feat target chip <<< "$(just _info {{board}})"; \
     case "$target" in \
         xtensa-*) \
-            port=$(just _find_port "303a:1001" "1209:5741" "10c4:ea60"); \
+            port=$(just _find_port "303a:1001" "1209:5741" "10c4:ea60" "1a86:7522" "1a86:7523"); \
             if [ -n "$port" ]; then \
                 echo "Using $port"; \
                 espflash flash -p "$port" "{{builds_dir}}/donglora-{{board}}-v{{version}}.elf"; \

src/board/elecrow_thinknode_m2.rs

@@ -1,8 +1,8 @@
 //! ELECROW ThinkNode-M2 — ESP32-S3 Meshtastic handset with SH1106 OLED.
 //!
 //! Tamagotchi-form-factor handheld: ESP32-S3-WROOM-1-N4 + SX1262 + 1.3" SH1106
-//! OLED + CP2102 UART bridge + 1000 mAh Li-Po. Sold pre-loaded with Meshtastic;
-//! this firmware turns it into a DongLoRa radio bridge.
+//! OLED + WCH CH340K UART bridge + 1000 mAh Li-Po. Sold pre-loaded with
+//! Meshtastic; this firmware turns it into a DongLoRa radio bridge.
 //!
 //! Pin map (verified from Meshtastic's variants/esp32s3/ELECROW-ThinkNode-M2
 //! and PR meshtastic/firmware#6354):
@@ -11,7 +11,7 @@
 //!   LoRa pwr: GPIO48 (must be HIGH before any SPI traffic)
 //!   OLED:     I2C0 SDA=16, SCL=15, SH1106 @ 0x3C
 //!   VEXT:     GPIO46 (active HIGH — gates OLED supply)
-//!   UART:     TX=43, RX=44 via CP2102 bridge
+//!   UART:     TX=43, RX=44 via CH340K bridge (USB 1a86:7522)
 //!   LED:      GPIO6 (active HIGH indicator)
 //!
 //! Notable differences from the Heltec ESP32-S3 boards: