Skippable Home Assistant first-run setup wizard + global HA connection status indicator

[riccardoaran]

Home Assistant is expected to be the primary (and initially the only) external service supported by Edge Mining. Since the HA connection is fundamental for core features (energy monitoring, miner control via smart plugs, etc.), we should guide users to connect HA as the first step when opening Edge Mining for the first time.

At the same time, this setup must be skippable so users can explore the UI without configuring anything yet.

In addition, the UI should always expose a clear, global indication of whether Home Assistant is connected or not (green/red), with quick access to connection details.

See the sub-issues for details.

[riccardoaran]

In the bottom-right corner.

[markoceri]

This requires the state to be provided by a Core API (edge-mining/core#65)

[riccardoaran]

Is it something that @sebailfico you can do?

[markoceri]

Added visualization of the connection status with external services (Home Assistant). The colors change based on the status.

I've also added the app version (core and frontend) to the same bar.

[GitGab19]

Where did you add this? Without a PR mentioning this issue, it's very hard to know what's going on.

[markoceri]

PR #15 partially closes this issue for the part regarding the status indicator.