[GrantFox][Medium] Make prediction cards accessible without color dependence

Summary

Make prediction cards accessible without color dependence

Why this matters

Market status, probability, and outcome affordances must work for keyboard and screen-reader users.

Scope

Add semantic labels, focus order, text alternatives, and contrast-safe states.

Acceptance criteria

• Every probability/status has a textual equivalent.
• Keyboard users can inspect and activate actions.
• Focus is visible and preserved.
• Automated accessibility tests cover active, closed, and settled states.

Validation

Add regression coverage for existing behavior, failure modes, authorization boundaries, and compatibility. The implementation must pass the repository CI checks.

Non-goals

• Typo-only, formatting-only, or documentation-only changes.
• Unrelated refactors or dependency upgrades.
• Weakening existing security, authorization, CI, or production safeguards.

Contributor application

Before implementation, comment with relevant experience, a 1–4 bullet approach, and an estimate for opening the first draft PR. Wait for maintainer assignment before coding.

PR requirements

Use a feature branch, include Closes #<issue-number>, check every acceptance criterion, link criteria to code/tests, explain security and failure-mode considerations, and pass CI.

Reward-readiness

This is a substantive GrantFox campaign issue. Merge and CI success do not by themselves guarantee reward eligibility; final reward-readiness is determined by campaign review.

Start by locating the prediction card components and the existing accessibility test setup. Trace active, closed, and settled states, then define coverage for textual equivalents, keyboard activation, visible focus, and contrast-safe states. Done means all acceptance criteria are covered by regression tests and the repository CI checks pass.