fix: refresh active sessions after revocation

[dollarop]

Closes #908

Summary

• re-fetch active sessions after successful single-session revocation
• re-fetch after revoking all other sessions
• keep the affected action disabled while the authoritative refresh is in flight
• add regression coverage for both revoke flows

Validation

• npm test -- --runTestsByPath __tests__/SessionManager.test.tsx (2 tests passed)
• npx eslint components/SessionManager.tsx
• git diff --check

The repository-wide type-check currently reports numerous unrelated errors already present on upstream main; the new test's local SessionInfo fixtures were corrected and the focused suite passes.

[github-actions]

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