Franknoirot/fix onboarding units (#366)

* Fix up camera step copy and pane opacity for step

* Fix broken onboarding redirect with double slash

* Fix pane height for web bug from blur filter
I found a bug with browser behavior, at least on Chrome.
If you use `backdrop-filter: blur()` at all, you can't
have any children that overflow. The browser will ignore
any attempt and make those children max full-height.
This broke our side panels after I added blur, but
only in Chrome/browser target.

Signed-off-by: Frank Noirot <frank@kittycad.io>

* Fix bug with unit system
Changing the unit system didn't also change the
base unit in the onboarding anymore. It needed
updated to use XState the same way as `/settings`

Signed-off-by: Frank Noirot <frank@kittycad.io>

* Fix AppHeader item spacing when there's no toolbar

---------

Signed-off-by: Frank Noirot <frank@kittycad.io>

src/components/AppHeader.module.css

@@ -3,6 +3,5 @@
   in Tailwind, such as complex grid layouts.
  */
 .header {
-  display: grid;
   grid-template-columns: 1fr auto 1fr;
 }