[Feature/Improvement] Improve Audio Files

**Purpose:** As a user, I want sound effects to be smooth and consistent so that audio cues are clear and never skipped.

**More details:** Currently, sound effect files vary in length and some start or end abruptly, creating harsh or jarring audio experiences. All sound effect files should be trimmed to a consistent, short duration and processed with fade in/fade out envelopes to ensure clean playback.

**Acceptance Criteria:**
- All sound effect files are under 500ms (0.5 seconds) in duration
- All sound effect files have a fade in applied at the start to prevent clicking or abrupt onset
- All sound effect files have a fade out applied at the end to prevent clipping or abrupt cutoff
- Fade durations are consistent across all files (e.g. 10–20ms fade in, 20–30ms fade out)
- All updated files are verified to play without audible pops, clicks, or harsh transitions on both iOS and Android