feat: add configurable PR status animation sound

[Dao-you]

Motivation

• Provide an audible cue when a PR status animation is shown so users can be alerted to updates by default sound or custom audio.
• Allow users to control the feature from the settings panel (enable/disable, upload local audio, restore default, preview) and persist choices across sessions.

Description

• Added settings UI in src/views/DashboardView.vue for "動畫音效" with a toggle, file upload (audio/*), a "恢復預設音效" button and a preview button, and a label that shows the current sound name.
• Introduced new localStorage keys tattoo-dashboard-status-animation-sound-enabled, tattoo-dashboard-status-animation-sound-data-url, and tattoo-dashboard-status-animation-sound-name and a default sound path /cash.mp3 (file placed under public/cash.mp3).
• Implemented client-side file reading to Data URL for uploaded audio, storing the Data URL and file name in localStorage, and managing an HTMLAudioElement to preload/play the selected sound.
• Hooked playback into the existing animation flow so playStatusAnimationSound() is invoked when triggerPrStatusAnimation() runs, and added preview/play utilities (previewStatusAnimationSound, uploadStatusAnimationSound, clearCustomStatusAnimationSound, applyStatusAnimationSoundEnabled).

Testing

• Ran npm run build which completed successfully and produced the dist artifacts.
• Launched the dev server and captured a settings modal screenshot with an automated Playwright script showing the new sound controls (screenshot artifact saved).
• Verified .github/workflows/deploy-pages.yml still runs npm run build and uploads dist, preserving Pages workflow compatibility.

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Codex Task