Implement Error Toasts

[PauloMFJ]

Overview

Adds a lightweight in-house toaster (foundations/toaster) based on Sonner.

• Stacked toasts that collapse into a scaled pile and fan out on hover/focus, with enter/exit animations and pause-on-interaction
• Click anywhere to dismiss (keyboard-accessible) + auto-dismiss timer
• a11y: labelled aria-live region, per-toast dismiss labels, focus-aware expand/pause
• Reduced motion: identical behaviour, just without durations
• Adds toaster-* color tokens, a type-headline mixin, and a $z-index-toaster token
• Fixes the card export / view-chart actions (onclick → onClick) that silently never fired

Screenshots

[gemini-code-assist]

Code Review

This pull request introduces a stacked Toaster notification system, adds zoom and tool Controls to the Atlas editor, updates the Button component to support multiple sizes, and introduces several new icons and color tokens. Feedback on these changes highlights critical issues: in toaster.tsx, the container height calculation when collapsed creates an invisible pointer-blocking area, and the heights state suffers from a memory leak as dismissed toast heights are never cleaned up. Additionally, in atlas.tsx, a CSS variable is incorrectly used for canvas rendering where static RGB values are required, and in button.tsx, making the new size prop required introduces a breaking change that should be resolved by making it optional with a default value.

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[nick-nlb]

We can discuss the bigger comment and keep it for another PR, but otherwise the one smaller behavioral comment.

Do you mind also taking some screenshots and including them in the description here, and then pinging miss-o-soup to have a look (in case this is completely new UI/UX). Alternatively, since we're meeting tomorrow anyway, you could give it a demo then.

[nick-nlb]

Thanks Paulo!