HTML output filename

[tguichaoua]

Add html_output field to config to define the filename of the output HTML file.
When the field is not defined, it uses the same filename as the target HTML file.

[dVeon-loch]

@ctron @tguichaoua Could you clarify the motivation behind the html_output change?

In many workflows (including mine), trunk serve expects dist/index.html by default. The new behavior breaks this unless html_output is explicitly set. Was this change intended to support multi-page apps, or is there another use case where renaming the output is beneficial?

It might be preferable to change the behaviour of this config to match the previous behaviour (e.g. if this config is not included, then default to renaming to index.html)

If reverting the default behavior isn’t possible, could we add a warning when html_output isn’t set? For example:

Warning: No `html_output` specified. The output file will be named after the source HTML file.
To generate `index.html`, add `html_output = "index.html"` to your `Trunk.toml`.

This would help users quickly identify and fix the issue.

[ctron]

When the field is not defined, it uses the same filename as the target HTML file.

I think this was not intentional. Maybe needs to be fixed? @tguichaoua

[dVeon-loch]

When the field is not defined, it uses the same filename as the target HTML file.

I think this was not intentional. Maybe needs to be fixed? @tguichaoua

@ctron I have created a PR to fix this behaviour here: #955

Please let me know if it looks good