feat: add factory reset serial command

'factory reset' clears all NV settings to 0xFF and writes to EEPROM
immediately, then re-initializes defaults via Reflow_ValidateNV().

Essential when upgrading from stock or pre-v2.0 firmware where the
EEPROM layout is different and values would be misinterpreted.

Author: ImNoahDev

src/main.c

@@ -98,6 +98,7 @@ static char* help_text = \
 " pidtune                 Run PID auto-tune\n" \
 " tccal                   Run TC offset auto-calibration\n" \
 " values                  Dump currently measured values\n" \
+" factory reset            Reset all settings to defaults\n" \
 "\n";
 
 
@@ -616,6 +617,12 @@ static int32_t Main_Work(void) {
 			} else if (strcmp(serial_cmd, "backup") == 0) {
 				FlashProfiles_BackupAll();
 
+			} else if (strcmp(serial_cmd, "factory reset") == 0) {
+				NV_FactoryReset();
+				Reflow_ValidateNV();
+				Reflow_LoadCustomProfiles();
+				printf("\nReboot recommended.\n");
+
 			} else {
 				printf("\nCannot understand command, ? for help\n");
 			}

src/nvstorage.c

@@ -94,3 +94,9 @@ int32_t NV_Work(void) {
 	}
 	return nvupdatepending ? (TICKS_SECS(2)) : -1;
 }
+
+void NV_FactoryReset(void) {
+	memset(myNV.config, 0xff, NVITEM_NUM_ITEMS);
+	EEPROM_Write(NV_STORAGE_OFFSET, (uint8_t*)&myNV, sizeof(myNV));
+	printf("\nFactory reset complete — all settings cleared to defaults.\n");
+}

src/nvstorage.h

@@ -45,5 +45,6 @@ void NV_Init(void);
 uint8_t NV_GetConfig(NVItem_t item);
 void NV_SetConfig(NVItem_t item, uint8_t value);
 int32_t NV_Work(void);
+void NV_FactoryReset(void);
 
 #endif /* NVSTORAGE_H_ */