fix: restore sound settings panel and play sound only on merge animations

[Dao-you]

Motivation

• Restore the missing status-animation sound controls in Settings so users can enable/disable, upload, preview and reset animation sounds.
• Ensure automatic sound playback only triggers for merge animations (avoid playing sound on other animation types).

Description

• Restored the sound UI in the settings modal: enable toggle, file upload (<input type="file" accept="audio/*">), preview and reset buttons, and current-sound label in src/views/DashboardView.vue.
• Play logic changed so playStatusAnimationSound() is invoked only when the detected animation effect === 'merged' inside triggerPrStatusAnimation in src/views/DashboardView.vue.
• Replaced direct writes to the computed token message with setTokenMessageText(...) for sound-related messages to ensure message state updates correctly.
• Added i18n keys for the new settings strings (zh / en / wzh) in src/services/i18n.ts so the restored UI is localized.

Testing

• Ran the production build with npm run build and it completed successfully (Vite build succeeded).
• Verified Pages workflow expectations by checking package.json scripts and .github/workflows/deploy-pages.yml to confirm npm run build and dist artifact use remain intact.
• Started the dev server and captured a Playwright screenshot of the settings panel to validate the restored UI, which completed without errors.

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Codex Task