Add staking estimator, dashboard tests, and SEP-10 nonce guard

[wheval]

Summary

• added a dashboard staking yield estimator with deposit and lock-duration controls
• added focused dashboard tests for the staking estimator, dashboard placement, and existing theme coverage
• stored SEP-10 challenge nonces in Redis with a five-minute TTL and consumed them during token verification to prevent replay
• fixed the JWT blacklist logger call so the auth controller test compiles

Validation

• ../node_modules/.bin/vitest run src/components/StakingCalculator.test.tsx src/components/DashboardOverview.test.tsx src/contexts/ThemeContext.test.tsx — 29 passed
• npm run pretest in backend — Prisma Client generated
• ../node_modules/.bin/jest --config jest.config.js --runInBand --runTestsByPath src/api/controllers/auth.controller.test.ts --coverage=false — 9 passed
• ../node_modules/.bin/vitest run in dashboard — 429 passed, 31 failed in existing areas outside this change, including App uiConfig, FlashLoan contract-address fixtures, CircuitBreaker mock expectations, and timer-sensitive component tests

Notes

This adds focused component coverage for the dashboard changes, but repo-wide dashboard coverage was not verified because the existing full dashboard suite is failing before coverage can be trusted.

Closes #1238
Closes #1234
Closes #1229
Closes #1177

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