ci: add raspberrypi-pico-2 to nuttx build matrix (#4721)
Add Raspberry Pi Pico 2 (Cortex-M33) board configuration to the NuttX CI build matrix to ensure WAMR compatibility testing covers the Cortex-M33 platform. The board configuration path "boards/arm/rp23xx/raspberrypi-pico-2/configs/nsh" is inserted after the cortex-m7 configuration to maintain logical architecture ordering.