refactor: replace toggle with chevron for show variants in Hub

[Lokimorty]

Describe Your Changes

The "Show variants" toggle in Hub uses a Switch component, but toggle is not the right design pattern here. Toggles are for settings that apply immediately—in this context we're just expanding a layout to show more content.

Replaced the Switch with a clickable chevron:

• Text "Show variants" with chevron icon to the right
• Entire line is clickable, not just the icon
• Chevron points down when collapsed, up when expanded
• Matches styling of other icons in the row (size 18, text-main-view-fg/50 color)

To test it:

1. Open Hub
2. Find a model with multiple variants (look for variant count > 1)
3. Click "Show variants" text or the chevron
4. Verify the variants list expands and chevron flips to point up
5. Click again to collapse

Fixes Issues

Self Checklist

• Added relevant comments, esp in complex areas
• Updated docs (for bug fixes / features)
• Created issues for follow-up changes or refactoring needed

[Vanalite]

I agree that the chevron up/down looks more reasonable than a toggle, but it this icon is too off, blended to the text and background that users might not notice @Lokimorty

[Lokimorty]

From my point of view:

Variants is a secondary feature — casual users don't need it, and the segment of users that does will look for it specifically which will make it hard to miss. We want it accessible but not competing for attention with the other elements in the card

With the chevron icon I prioritized consistency (of color, size) with other icons in this card

I can see an option where we align "Show variants" to the right end of the card to highlight it using the hierarchy. This way we can make it more visible without changing the color or size to keep it consistent. Let me know if you see it differently @Vanalite

[Vanalite]

@Lokimorty You make a good point of "We want it accessible but not competing for attention with the other elements"
Pls update your branch with your suggestion and we will look into it again

[Lokimorty]

@Vanalite updated