build: add standalone script to clear sd card

sphinx-key/clear_sd.sh

@@ -0,0 +1,34 @@
+check_exists() {
+    command -v "$1" > /dev/null
+}
+check_port() {
+    cargo espflash board-info --port "$1" &> /dev/null
+}
+if ! check_exists esptool.py
+then
+    echo "esptool.py not installed!"
+    echo "install with this command: pip install esptool"
+    exit 1
+fi
+if ! check_exists ldproxy
+then
+    echo "ldproxy not installed!"
+    echo "install with this command: cargo install ldproxy"
+    exit 1
+fi
+if ! check_exists cargo-espflash
+then
+    echo "cargo-espflash not installed!"
+    echo "install with this command: cargo install cargo-espflash"
+    exit 1
+fi
+if ! check_exists espflash
+then
+    echo "espflash not installed!"
+    echo "install with this command: cargo install espflash"
+    exit 1
+fi
+cargo espflash save-image --bin clear --release --chip esp32c3 clear.bin &&
+espsecure.py sign_data clear.bin --version 2 --keyfile ../secure_boot_signing_key.pem &&
+espflash write-bin 0x50000 clear.bin &&
+cargo espflash monitor