Add wifi hostname change and persistence between reboot

[vcarriere]

Added the hostname handler in Wifi controller
Added logic in main.cpp to fetch hostname from NVS and apply it before the wifi is used
Added a argtransformer function to check if the string is alphanumeric only
Added the help description
Added globalstate for hostname

[vcarriere]

Ok, I resolved all my previous issues and I think this is a clean way.

[geo-tp]

Thanks for the contrib,

Could you first clarify the intended use case: setting a persistent hostname before connecting in Wi-Fi Client/Web UI mode, changing it at runtime, or both ?

void WifiController::handleHostname(const TerminalCommand &cmd)
{
    const std::string hostname = cmd.getSubcommand();

    if (hostname.empty()) {
        terminalView.println("Usage: hostname <name>");
        return;
    }

    if (hostname.length() > 32) {
        terminalView.println("Invalid hostname. Maximum 32 characters.");
        return;
    }

    if (hostname.front() == '-' || hostname.back() == '-') {
        terminalView.println("Invalid hostname. Cannot start or end with '-'.");
        return;
    }

    for (char c : hostname) {
        if (!(argTransformer.isValidAlphanumeric(std::string(1, c)) || c == '-')) {
            terminalView.println("Invalid hostname. Use letters, numbers, and '-' only, ");
            return;
        }
    }



    // Save hostname to NVS and set it
    nvsService.open();
    nvsService.saveString(GlobalState::getInstance().getNvsHostnameField(), hostname);
    nvsService.close();
    WiFi.setHostname(hostname.c_str());

    terminalView.println("WiFi: Hostname set to: " + wifiService.getHostname());
    terminalView.println("\n [⚠️  WARNING] ");
    terminalView.println(" Restart your device for hostname change to take effect.*\n");
}

WifiController should not call the Arduino WiFi API directly or know which library implements Wi-Fi. It should only interact with IWifiService

Also, it would be better to handle the hostname parsing and validation with something like argTransformer.isValidHostname`, even if the current way (validating in the controller) is also acceptable.

One last question: would it make more sense to configure the hostname when entering Wi-Fi mode or through config cmd, rather than exposing a standalone hostname command?

Since the hostname must be applied before connecting, changing it while using the Web CLI or when already connected would most likely require a reconnection to take effect