VesiScan BASIC origin: Piezo + IMU firmware initial code

- nRF52840 + SoftDevice S140 BLE firmware
- Piezo ultrasound TX driver (2MHz, 8ch MUX)
- ICM42670P IMU 6-axis driver
- Echo AFE chain (ADA2200 + ADC121S051)
- BLE NUS command parser (mpa/mpc/mdc/mec/maa/msp)
- FDS flash config storage
- pc_firm parser and ADC driver included

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pc_firm/mt_nirs.code-workspace

@@ -0,0 +1,11 @@
+{
+	"folders": [
+		{
+			"path": "../mt_nirs"
+		},
+		{
+			"path": "."
+		}
+	],
+	"settings": {}
+}