Add responsive sTEZ layout and global footer

[KevinMehrabi]

What changed

• reorganizes the sTEZ page into a responsive desktop workspace with the action panel on the left and protocol context on the right
• adds the global TEZEX footer across application routes
• uses the supplied modern Tezos horizontal logo with theme-appropriate white and black SVG variants
• keeps the footer compact on mobile while aligning TEZEX, navigation, and the Tezos endorsement across the desktop layout

Why

The sTEZ experience needed to follow the established desktop swap layout instead of remaining a narrow stacked mobile composition. The site also needed a consistent global footer and the current Tezos brand treatment.

Validation

• npm audit --omit=dev --audit-level=high
• npm run typecheck
• npm run test:ci — 22 suites, 65 tests passed
• npm run build
• dark/light and desktop/mobile visual verification