feat: add Wi-Fi SoftAP provisioning

[IM-TechieScientist]

Working on #208.

Adds first-run Wi-Fi provisioning to the ESP32 SPI bridge.

Instead of compiling station credentials into the firmware, a board without
saved credentials now starts a temporary WPA2 setup access point named:

PSLab-Pico-XXXX

The user connects to that access point and opens http://192.168.4.1 to enter
the target Wi-Fi SSID and password. Credentials are stored in ESP NVS and the
bridge then switches to normal station mode.

Changes:

• Add a dedicated wifi_provisioning module.
• Store and load station credentials from ESP NVS.
• Start a temporary SoftAP only when credentials are missing.
• Serve a minimal browser based setup form at 192.168.4.1.
• Reenter provisioning after saved credentials repeatedly fail to connect.
• Remove compile time SSID/password configuration.

Summary by Sourcery

Add first-run Wi-Fi SoftAP provisioning to the ESP32 SPI bridge so boards can be configured via a local web setup page and then connect as Wi-Fi stations using stored credentials.

New Features:

• Introduce a Wi-Fi provisioning module that starts a temporary WPA2 setup access point and serves a browser-based configuration page.
• Persist user-entered station SSID and password in ESP NVS for reuse across boots.
• Automatically fall back to the provisioning access point when no credentials are stored or saved credentials fail to connect.

Enhancements:

• Refactor Wi-Fi startup to separate station connection logic from overall Wi-Fi initialization and provisioning flow.

Build:

• Register the new Wi-Fi provisioning component in CMake and declare required ESP-IDF dependencies for Wi-Fi, HTTP server, networking, timers, and NVS.

Documentation:

• Update firmware README with instructions for using the temporary provisioning access point and web setup page, including default password configuration.

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Reviewer's Guide

Implements first-run Wi-Fi SoftAP provisioning on the ESP32 bridge by introducing a dedicated provisioning module that serves a minimal HTTP form, persists credentials in NVS, and integrates with the existing Wi-Fi startup flow to switch between AP provisioning and normal station mode based on saved credentials and connection success.

Sequence diagram for Wi-Fi startup and SoftAP provisioning flow

sequenceDiagram
    participant ESPMain as main.c
    participant WifiProv as wifi_provisioning
    participant NVS as nvs
    participant WiFi as esp_wifi

    ESPMain->>WifiProv: wifi_provisioning_load_credentials(credentials)
    WifiProv->>NVS: nvs_open / nvs_get_str
    NVS-->>WifiProv: ssid/password or error
    WifiProv-->>ESPMain: loaded? (bool)

    alt no saved credentials
        ESPMain->>WifiProv: wifi_provisioning_run(credentials)
        WifiProv->>WiFi: esp_wifi_set_mode(WIFI_MODE_AP)
        WifiProv->>WiFi: esp_wifi_set_config(WIFI_IF_AP, ap_config)
        WifiProv->>WiFi: esp_wifi_start()
        WifiProv->>WifiProv: start_server()
        WifiProv-->>ESPMain: credentials
    end

    ESPMain->>WiFi: start_station(credentials)
    WiFi-->>ESPMain: connected? (bool)

    alt saved station connection failed
        ESPMain->>WifiProv: wifi_provisioning_run(credentials)
        WifiProv-->>ESPMain: new credentials
        ESPMain->>WiFi: start_station(credentials)
    end

Loading

Sequence diagram for HTTP-based credential provisioning

sequenceDiagram
    actor User
    participant AP as SoftAP_192_168_4_1
    participant Httpd as esp_http_server
    participant WifiProv as wifi_provisioning
    participant NVS as nvs

    User->>AP: Connect to PSLab-Pico-XXXX
    User->>Httpd: GET /
    Httpd->>WifiProv: setup_page_handler()
    WifiProv-->>Httpd: setup_page (HTML)
    Httpd-->>User: Wi-Fi setup form

    User->>Httpd: POST /configure (ssid, password)
    Httpd->>WifiProv: configure_handler(request)
    WifiProv->>WifiProv: get_form_value("ssid") / get_form_value("password")
    WifiProv->>WifiProv: credentials_are_valid()
    WifiProv->>NVS: nvs_set_str / nvs_commit
    NVS-->>WifiProv: ESP_OK
    WifiProv->>WifiProv: xEventGroupSetBits(PROVISIONING_COMPLETE_BIT)
    WifiProv-->>Httpd: httpd_resp_sendstr("Saved")
    Httpd-->>User: Confirmation page

Loading

File-Level Changes

Change	Details	Files
Refactor Wi-Fi startup logic to support credential-based station startup and provisioning fallback.	Replace compile-time SSID/password use with a credentials struct passed into station startup. Add start_station() that configures and starts the STA interface, waits for connection bits, and cleanly stops Wi-Fi on failure. Extend start_wifi() to initialize netif/event loop, create both AP and STA interfaces, register Wi-Fi/IP event handlers, and orchestrate loading credentials and running provisioning when needed. Handle initial missing credentials by starting provisioning, then joining STA with returned credentials; on failed STA connection, re-enter provisioning and retry.	esp_firmware/main/main.c
Add a Wi-Fi provisioning module that exposes NVS-backed credential loading and an interactive SoftAP-based configuration flow via HTTP.	Define wifi_provisioning_credentials_t and public APIs wifi_provisioning_load_credentials() and wifi_provisioning_run(). Implement NVS storage helpers to save and load SSID/password with basic validation on retrieved credentials. Start a temporary WPA2 SoftAP with a MAC-derived SSID and configurable password, using the pre-created AP netif and esp_wifi APIs. Run an embedded HTTP server that serves a minimal HTML setup page and a POST endpoint that parses application/x-www-form-urlencoded SSID/password, validates input length, saves to NVS, and signals completion via an event group. Ensure Wi-Fi AP and HTTP server are stopped on completion or error, returning the selected credentials to the caller.	esp_firmware/main/wifi_provisioning.c esp_firmware/main/wifi_provisioning.h
Update build configuration and documentation for runtime Wi-Fi provisioning and new module dependencies.	Add wifi_provisioning.c to the main component sources and declare required ESP-IDF components such as esp_http_server, esp_wifi, esp_netif, lwip, and nvs_flash. Document first-boot SoftAP behavior, setup URL, default provisioning password, and automatic fallback to provisioning when saved credentials fail. Remove references to compile-time station SSID/password configuration from the README and associated Kconfig/sdkconfig defaults entries.	esp_firmware/main/CMakeLists.txt esp_firmware/README.md esp_firmware/main/Kconfig.projbuild esp_firmware/sdkconfig.defaults

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