feat: implement Wi-Fi provisioning and persistent configuration

README.md

@@ -1,8 +1,8 @@
 # maze32
 
-maze32 is an ESP32-C6-hosted browser maze game. The current firmware skeleton
-mounts a LittleFS image, serves a compressed static page, and exposes a bounded
-`/health` response containing the firmware version and startup state.
+maze32 is an ESP32-C6-hosted browser maze game. The firmware mounts LittleFS,
+serves compressed local pages, exposes a bounded health response, and connects
+to saved Wi-Fi credentials or starts a fallback provisioning access point.
 
 ## Prerequisites
 
@@ -60,7 +60,38 @@ Monitor startup at 115200 baud:
 /home/sasa/.platformio/penv/bin/pio device monitor
 ```
 
-A successful boot reports the firmware version, LittleFS capacity and use, the
-HTTP service startup, and health state `serving`. Network provisioning is part
-of a later milestone; this milestone only establishes the HTTP/static service
-that will be attached to that network lifecycle.
+A successful boot reports the firmware version, LittleFS capacity and use,
+network state, HTTP service startup, and health state `serving`.
+
+## Wi-Fi provisioning and recovery
+
+With no saved credentials, or after a failed station connection, the device
+starts an open access point named `maze32-XXXX`, where `XXXX` comes from the
+device MAC address. Connect to it and open:
+
+```text
+http://192.168.4.1/provision
+```
+
+Scan for nearby networks, select or enter an SSID, and save the password. The
+device stores a schema-versioned configuration in NVS and retries in station
+mode. If the attempt fails, the fallback access point returns automatically.
+After a successful connection, `/api/wifi/status` reports the station address.
+
+To recover from obsolete or incorrect credentials, reconnect to the fallback
+access point after the failed attempt and use **Удалить настройки сети**. The
+same reset operation is available as `POST /api/wifi/reset`. Saving or clearing
+credentials always invokes the runtime reconfiguration guard first; a future
+active match service can reject the operation until it has explicitly stopped
+the match.
+
+The isolated on-device NVS/reboot diagnostic uses a deliberately unavailable
+SSID, refuses to overwrite unexpected saved credentials, and clears its test
+record after verifying fallback recovery:
+
+```sh
+/home/sasa/.platformio/penv/bin/pio run -e milestone-003-device-test
+/home/sasa/.platformio/penv/bin/pio run -e milestone-003-device-test --target upload
+```
+
+Restore the normal firmware afterward with the standard upload command.