Add sTEZ protocol interface

[KevinMehrabi]

What changed

• adds sTEZ as a separate top-level desktop and mobile navigation tab
• reads sTEZ capability, contract, rate, supply, backing, and connected-wallet position from one fixed Tezos RPC block
• presents Stake, Redeem, and Finalize flows with protocol-accurate terminology and state explanations
• renders explicit disabled, unsupported, and unreachable states without invented balances, rates, contracts, or history
• adds responsive light/dark styling and correct RPC attribution

Safety boundary

Mainnet currently exposes the Ushuaia protocol but has not activated its native sTEZ contract. The page therefore reports the real unavailable state. Transaction signing remains intentionally disabled until an enabled sandbox provides validated operation schemas, simulations, and fixtures.

Verification

• TypeScript typecheck
• 62 automated tests across 20 suites
• optimized production build
• production dependency audit at the configured high-severity threshold
• desktop and mobile visual QA in light and dark themes
• live Mainnet capability check through the configured RPC failover set