dietpi-network: new tool for multi interface configuration

[Copilot]

DietPi-Config's Menu_NetworkAdapters hardcoded exactly one Ethernet and one WiFi interface (resolved via G_GET_NET prefix matching), stored everything in a single /etc/network/interfaces, and had no non-interactive way to change settings.

New dietpi/dietpi-network script

• Extracted Menu_NetworkAdapters/_Ethernet/_Wifi/_Proxy and all exclusive helpers/state out of dietpi-config into a standalone script, structured like dietpi-vpn/dietpi-ddns.
• dietpi-config now execs /boot/dietpi/dietpi-network where Menu_NetworkAdapters used to be called; all related TARGETMENUID handling is removed.

Per-interface, name-independent configuration

• Interfaces are enumerated via /sys/class/net/* instead of G_GET_NET: WiFi = has a wireless subdir, Ethernet-like = has a device subdir but no wireless. Works with systemd predictable names (enp3s0, wlp2s0, ...), not just eth*/wlan*.
• Every detected interface gets its own submenu, so multiple Ethernet and/or WiFi adapters are configurable independently.
• Added a global WiFi toggle, decoupled from any specific adapter.

Storage moved to per-interface drop-ins

• Settings are written to /etc/network/interfaces.d/<name>.conf instead of rewriting /etc/network/interfaces wholesale.
• If an interface is already defined in /etc/network/interfaces, its config is read from there for the submenu; applying settings removes that interface's block from /etc/network/interfaces to avoid duplicate definitions.

New CLI

• Any submenu can be opened directly: dietpi-network <ifname|proxy|wifi|country|test>.
• Settings changeable non-interactively, e.g.:

  dietpi-network apply wlan0 --enable --static --hotspot --ip 192.168.42.1 --mask 255.255.255.0
  dietpi-network wifi disable
  dietpi-network proxy address proxy.example.com
  

dietpi-software WiFi Hotspot

• Install/uninstall now detects the WiFi interface via /sys/class/net/*/wireless and delegates interface configuration to dietpi-network apply ... --hotspot/--client instead of editing /etc/network/interfaces directly.

Other

• Added dietpi-network shell alias alongside the other DietPi CLI tools.
• dietpi-set_hardware eth-forcespeed now accepts an explicit interface argument, since multiple Ethernet interfaces can exist.

[MichaIng]

@copilot
Please address my new comments.

Additionally:

• Add a new CLI option to dietpi-wifidb, to pass an explicit WiFi interface name, replacing the G_GET_NET -t wlan iface call if given. Use that in dietpi-network when called from a particular interface submenu.
• Migrate Allo_Main in dietpi/func/dietpi-set_software to the new dietpi-network CLI as well. Use G_GET_NET -t eth iface to obtain the interface to apply settings to.
• Add an additional option to remove an interface configuration entirely, instead of just disabling it.
• If two interfaces are enabled on the same subnet, they cannot both have the same gateway/default route (unless we implement a metric option), and more importantly, the duplicate LAN routes like 192.168.1.0/24 on two interfaces can cause asymmetric traffic, that way break communication with e.g. a connected SSH client. Until we implement some more complex e.g. routing table based solution for this, it hence needs to be avoided that two interfaces are enabled on the same subnet. Please hence add the following: If another interface does already use the same subnet that is to be applied via static IP, or if an interface is to be enabled with DHCP while a default route is already assigned to another interface, show an additional prompt with this information. Allow to ignore or disable the potentially conflicting interface, to proceed. If the user chooses to disable the conflicting interface, comment out the respective allow-hotplug/auto line, and ifdown --force that interface, before continuing to apply changes/enable the new interface.

[Copilot]

@copilot
Please address my new comments.
...

Addressed all points in ca6012f/9ed570b:

• dietpi-wifidb now supports -i <iface> to pass an explicit WiFi interface, used from dietpi-network's WiFi submenu instead of relying on auto-detection.
• Allo_Main in dietpi-set_software now uses G_GET_NET -t eth iface and delegates to dietpi-network apply.
• Added a "Remove" menu option (and it was already available via CLI remove) to delete an interface's stored configuration entirely, distinct from "Disable".
• Added Check_Network_Conflicts: when applying static IP/DHCP settings, if another enabled interface already uses the same subnet, or already has a default gateway while enabling DHCP, the interactive menu now shows a warning prompt to either ignore or disable the conflicting interface (commenting out allow-hotplug/auto and ifdown --forceing it) before proceeding; the CLI requires an explicit --force flag to bypass the check.