Replace ffaudio with ffmovie for PAGExporter audio encoding and update packaging scripts to share library with PAGViewer.

[CodeJhF]

移除 PAGExporter 对独立 ffaudio 库的依赖，改用 PAGViewer 已有的 ffmovie 库进行音频编码。更新打包脚本和安装逻辑，使两者共享 ffmovie 库以减小安装包体积。

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.90%. Comparing base (09c780a) to head (95a526c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3297      +/-   ##
==========================================
- Coverage   76.31%   74.90%   -1.42%     
==========================================
  Files         485      501      +16     
  Lines       28283    32765    +4482     
  Branches     8993    10701    +1708     
==========================================
+ Hits        21585    24543    +2958     
- Misses       4883     6040    +1157     
- Partials     1815     2182     +367     

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[CodeJhF]

修复了Discussion中用户反馈的音频导出问题。