feat: add module IWD

[waltmck]

Added module for controlling IWD over its dbus interface. This was made with Claude code, but is well-tested with several iterations of bug hunting. I also tried to match the structure and style of the existing Network module as closely as possible.

Closes #284.

[waltmck]

I am continuing to run this on my laptop and making some tweaks, but it is ready for review and testing by anyone who is interested.

A 5k LoC PR is understandably daunting from a maintenance burden perspective, especially if the current maintainers don't use IWD. I'm sympathetic to this, so it might be helpful to come up with a model of code ownership that would spread the work and make large contributions like this practical.

I would like to volunteer as a maintainer for this module: i.e., I promise to continually fix bugs and adapt to internal changes when necessary. If I am at some point unable to continue maintaining it, it should be very easy to remove since it is mostly self-contained: the only exception is this change to the Dashboard UI (making the quick connect widget fallback to using IWD when the Network module is unavailable), but I would be happy to remove that commit from the PR if it eases any maintainability concerns.