Add Storybook for the shared component library

[Dannyswiss1]

Set up Storybook in client/ and add stories for every component in client/src/components/ (Badge,
GlassCard, StatCard, Spinner, Toast, Modal, Navbar, LockaLogo, Icons), covering their meaningful
prop/state variants (e.g. every Badge tone, every WalletStatus for Navbar). This gives contributors and
designers a way to review UI changes in isolation against the reference design.

Acceptance criteria

• Storybook runs via npm run storybook from client/
• Every component listed above has at least one story
• Stories for stateful components cover their distinct visual states