PRXT - feat: improve filter target accessibility

[punk6529]

Summary

• replace the button-wrapped radios with a semantic fieldset, legend and individual radio inputs to enable native keyboard support
• ensure each radio shares a unique group name generated per render so only the intended option can be selected at once
• update the CommonFilterTargetSelect tests to cover the new group label and keyboard navigation behaviour

Testing

• npm run lint
• npm run type-check (fails: repository contains pre-existing type errors in test fixtures)
• npm run test (fails: many suites require BASE_ENDPOINT env var that is not configured in this environment)

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https://chatgpt.com/codex/tasks/task_e_68c9430aa9a08321ab6907bf81932241

[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 #1497