Announce wins and draws with an ARIA live region

[patchsmith-dev]

Goal

Make game results easier to detect for screen reader users.

Proposed behavior

• Add a polite live region near the status panel.
• Announce when black wins, white wins, or the game ends in a draw.
• Avoid repeating announcements on every render when the state has not changed.

Acceptance criteria

• Result changes are announced through a live region.
• Visual layout remains unchanged or minimally changed.
• Manual test notes are included in the pull request.

[patchsmith-dev]

Implemented in ef94f69. Wins and draws are now announced through a polite ARIA live region without repeating unchanged results. Local checks and GitHub CI passed, and Pages deployed successfully.