Rename board from ews_board to ews and fix board discovery

- Rename board directory: ews_board -> ews
- Rename board files: ews_board.dts -> ews.dts, ews_board_defconfig -> ews_defconfig
- Update board identifier and compatible strings
- Add board.cmake for runner configuration
- Set BOARD_ROOT in CMakeLists.txt to enable custom board discovery
- Update all documentation with new board name: west build -b ews

firmware/canfd_cdc_composite/boards/arm/ews/doc/index.rst

@@ -0,0 +1,47 @@
+# EWS Board
+
+## Overview
+
+The EWS Board is based on the STM32G0B1KBU6 microcontroller in UFQFPN32 package.
+
+## Hardware Features
+
+- STM32G0B1KBU6 MCU (Arm Cortex-M0+ core, 128 KB Flash, 36 KB RAM)
+- Internal HSI oscillator with USB clock recovery
+- USB 2.0 Full Speed interface
+- CAN FD interface  
+- Status LED on PB4
+- Two PFET control outputs (PA8, PB2)
+
+## Pin Configuration
+
+| Function | Pin | Notes |
+|----------|-----|-------|
+| Status LED | PB4 | Active high |
+| PFET1 Control | PA8 | Active high |
+| PFET2 Control | PB2 | Active high |
+| CAN RX | PB0 | FDCAN1_RX |
+| CAN TX | PB1 | FDCAN1_TX |
+| USB D- | PA11 | USB_DM |
+| USB D+ | PA12 | USB_DP |
+
+## Clock Configuration
+
+The board uses the internal HSI oscillator (16 MHz) with PLL to generate:
+- System clock: 64 MHz
+- USB clock: 48 MHz (from PLL Q output)
+- CAN clock: 64 MHz
+
+No external crystal is used; USB clock recovery ensures accurate timing for USB communication.
+
+## Programming and Debugging
+
+The board supports programming via:
+- USB DFU (built-in STM32 bootloader)
+- SWD interface (if exposed)
+
+## Building Firmware
+
+```bash
+west build -b ews
+```