Saga UI components

What this is

Svelte 5 components that implement the Saga product style. Each component renders the .saga-* classes from the style site's components.css and ships no CSS of its own, so a page here and the matching vanilla showcase page should look the same.

ComponentPackageSummaryShowcase
ConstellationBackground@saga-ed/constellation-bgDrifting-constellation login/landing background. `drift` and `field` modes, pause, reduced-motion aware.none yet

Planned: @saga-ed/ui-svelte wave 1 (Tooltip, Modal, Tabs, Skeleton, Toast, Select, DatePicker…) — see docs/decisions/phase-4-svelte-library.md.