PRXT - refactor: remove wallet cookie migration

[punk6529]

Summary

• remove legacy wallet cookie constants and migration logic so auth utilities rely solely on localStorage
• stop SeizeConnectContext from invoking the deleted cookie migration
• align auth and header tests with the localStorage-only implementation

Testing

• npm run lint
• BASE_ENDPOINT=http://localhost npx jest --runTestsByPath ./tests/services/auth.utils.test.ts ./tests/components/auth/SeizeConnectContext.test.tsx ./tests/components/header/share/HeaderShare.test.tsx --coverage=false --runInBand

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https://chatgpt.com/codex/tasks/task_e_68c94027e0a08321a409134b4800e968

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[prxt6529]

Will be done in #1516