feat(storybook): add display primitive stories

[myelinated-wackerow]

Summary

Adds Storybook stories for the display primitives in src/components/ui/. This is PR 3 of 5 for #18121, scoped to display components. One commit per checkbox in the issue.

• Tabs — Default, WithDisabledTab, ManyPanels (overflow scroll). Title UI / Primitives / Tabs.
• Skeleton — Default block, Lines, CardContent, Card, CardGrid sub-components. Title UI / Skeleton.
• Spinner — Default, Sizes (em-scaled), WithLabel, InsideButton. Title UI / Spinner.
• Progress — Default, Colors (disabled|primary), Values (0/25/50/75/100), WithLabel. Title UI / Primitives / Progress.
• Breadcrumb — TwoLevel, ThreeLevel, WithCurrentPage, WithEllipsis. Title UI / Primitives / Breadcrumb.
• ScrollArea — VerticalScroll, HorizontalScroll (explicit ScrollBar orientation), ShortContent. Title UI / Primitives / ScrollArea.
• List — Unordered, Ordered, Nested (mixed), PlainList. Title UI / List.
• Collapsible — Closed, Open (defaultOpen), WithCustomTrigger (data-state icon swap), ListOfDetails. Title UI / Primitives / Collapsible.
• TruncatedText — Default, OneLine, ThreeLines, FourLines, LineCounts (all 4 side-by-side), ShortText edge case. Title UI / TruncatedText.
• Chart — BarUsage, LineUsage, AreaUsage (stacked), PieUsage, TooltipIndicators (dot|line|dashed), HiddenLabel. Title UI / Chart.

Title hierarchy follows the convention established in #18122 / #18123: UI / Primitives / [Name] for shadcn-regenerable primitives, UI / [Name] for app-canonical components with custom shapes.

Notes for review

• Spinner has no built-in size prop; sizing is driven by font-size. Stories demonstrate scaling via Tailwind text-* utilities.
• TruncatedText uses client-side useTranslation for the Show more / Show less label; Storybook's preview wires next-intl so the toggle works without per-story setup.
• Collapsible WithCustomTrigger shows the canonical pattern for swapping chevrons via group-data-[state=open].
• ScrollArea horizontal scrolling requires an explicit ScrollBar orientation='horizontal'; the default ScrollBar is vertical-only.
• Breadcrumb uses the project's i18n-aware Link; the storybook preview wires next-intl so links render without errors.
• Chart stories reference colors via var(--color-<key>) CSS variables generated from the config map — designers can recolor a chart by editing the config without touching the Recharts JSX.

Test plan

• Eyeball each new story in Storybook (light + dark, locale toggle)
• a11y addon passes for each story
• Confirm TruncatedText toggle works with both Show more and Show less labels rendering

Refs: #18121

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