Add "Compile All" Button

**Describe the problem you have/What new integration you would like**

I would like to have a button in the dashboard similar to "Update All" but only for compiling.

**Please describe your use case for this integration and alternatives you've tried:**

To be honest the most time I wait when updating a device (ota) is when the code compiles.
I don’t like the button "Update All" because I want to see if the update process succeeds and my device is still reachable afterwards. So I want to compile the code of all my devices (best would be over night). Later then I would like to do the upload/flash process manually for each device.

I think it is somehow possible to do so over cli. But it looks complicated to me. And to have the possibility through the dashboard would be really nice 😃.

**Additional context**

Start by tracing the dashboard's existing "Update All" flow and the CLI compilation path mentioned in the request. Determine how compilation can be separated from upload/flash and what state the dashboard must expose; done means all selected devices can be compiled without flashing, with later manual uploads still possible.

Written by the indexing model from the issue text.