fix: wrapping and height calculations

[bashbunni]

Changes

Content used to cut off if the height of the window was smaller than the content height.
Wrapped content broke formatting and caused content to get cut off.
The offset calculations were off and wouldn't scroll to show hidden content.
There was an off by one error for content that exceeded the window height (would always hide the title of the first field).

Other considerations

Some fieds (confirm, select, input) have the option to be shown as inline. When shown as inline, the styles do not wrap (intentional)

Buttons will stack vertically if they don't fit horizontally. Button widths will also match (do we want that by default or only when stacked?)

Fixes

closes #398
closes #429

Maybe others (need to confirm)

Here's what this PR looks like:
https://github.com/user-attachments/assets/b3588782-33d4-4e11-8105-2f6b7335df6a

Previous behaviour:
https://github.com/user-attachments/assets/0e77808e-5895-45d4-b075-f299babecf2b

A few enhancements I'd still like to see: huh does a lot of redraws that cause rendering issues when not in alt screen. You come across that behaviour when resizing the window a lot while running an example (e.g. burger)

• feat: set group with from size msg
• feat: handle WindowSizeMsg + base height on rendered content
• feat: render prefix before newlines
• feat: update viewport on resize, cursor != height so no scroll...
• fix: always update viewport height
• fix: add option prefix
• fix(multiselect): width calculation
• fix: calculate offset from previous field heights
• feat: add calculate wrapping helper
• fix(select): wrap select field
• feat: make group set field widths accounting for styles
• feat: set width
• feat: stack buttons in narrow window
• feat: add Theme function to Fields
• feat: calculate width based on field theme
• fix(group): fix height calculation
• feat: remove FullWidth helper (not needed)
• fix(group): fix off by one at top for overflowed content

[bashbunni]

In case we don't want to merge the stacked buttons here, I have another version of this branch where I removed those features. https://github.com/charmbracelet/huh/tree/horizontal-btns

[bashbunni]

rip, looks like these changes might be breaking grid layout...

In the image above we're missing options 4-6. This is happening at all widths. Absolutely tragic 😭

Build info:
macOS, kitty, no multiplexer, just running the layouts/grid example

• add tests with outputs from examples

[bashbunni]

The grid rendering issue may be related to charmbracelet/bubbletea#573...

The fourth to sixth elements are shown when I print form.View, but for some reason when running the form it's cutting it off in the terminal window. I only see this in the terminal, but not when logging the output at all. You can see this by running go test -run TestLayoutGrid -v locally. That's the same code as the layout/grid example.

I thought it might be related to layoutGrid.visibleGroups, but I ruled it out (removed the condition + made it all visible)