feat(factory-cli): add Wi-Fi credential management commands

docs/factory-cli-wifi-commands.md

@@ -0,0 +1,73 @@
+# Factory CLI Wi-Fi Commands
+
+The Factory CLI accepts commands terminated by CR, LF, or CRLF on UART0. A
+successful command returns `OK`. Commands that return data emit one JSON line
+before `OK`. Failures return `ERROR <reason>`.
+
+## Read Saved Networks
+
+```text
+get_wifi
+```
+
+The response lists saved SSIDs in connection-priority order. Passwords are
+never returned. Up to 10 networks can be stored.
+
+```text
+{"count":2,"networks":[{"priority":0,"ssid":"Office WiFi"},{"priority":1,"ssid":"Backup"}]}
+OK
+```
+
+An empty list is returned as:
+
+```text
+{"count":0,"networks":[]}
+OK
+```
+
+## Save a Network
+
+```text
+set_wifi "Office WiFi" "network-password"
+```
+
+The SSID is required and may contain up to 32 bytes. The password may contain
+up to 64 bytes. Quote arguments that contain spaces. A missing or explicitly
+empty password saves an open network:
+
+```text
+set_wifi "Guest Network"
+set_wifi "Guest Network" ""
+```
+
+Backslash escapes the following character inside or outside quoted arguments.
+To include a literal backslash, enter it twice.
+
+Saving a new SSID inserts it at priority 0. Saving an existing SSID replaces
+its password and moves it to priority 0. If 10 networks are already saved,
+adding a new SSID removes the lowest-priority entry. This command only updates
+persistent credentials; it does not disconnect or immediately reconnect the
+current station.
+
+## Clear Saved Networks
+
+```text
+reset_wifi
+```
+
+This command clears all saved Wi-Fi credentials, returns `OK`, allows 100 ms
+for the UART reply to be transmitted, and restarts the device. It has the same
+persistence effect as the physical Wi-Fi reset action.
+
+## Error Responses
+
+| Response | Meaning |
+| --- | --- |
+| `ERROR invalid_command_syntax` | An argument quote was not closed or the command contains too many arguments. |
+| `ERROR wifi_read_failed` | Saved networks could not be read. |
+| `ERROR wifi_response_too_large` | The saved network response exceeded the internal reply buffer. |
+| `ERROR missing_wifi_ssid` | `set_wifi` did not receive a non-empty SSID. |
+| `ERROR invalid_wifi_arguments` | `set_wifi` received more than an SSID and password. |
+| `ERROR invalid_wifi_credentials` | The SSID or password exceeded its supported length. |
+| `ERROR wifi_save_failed` | Credentials could not be saved. |
+| `ERROR wifi_reset_failed` | Saved credentials could not be cleared. |