修复签名视频链接的解析路由 / Fix signed video URL parser routing

[KCHENPENGFEI]

中文：对 HTTP/HTTPS URL 使用 urlparse(url).path 提取扩展名，确保 video.mp4?signature=... 命中 UnderstandingAPI fast path。新增带签名视频 URL 的 ParserRouter 回归测试。

English: Parse HTTP/HTTPS URL paths before checking extensions so signed video URLs hit the UnderstandingAPI fast path. Add a ParserRouter regression test for signed video URLs.

Description

Related Issue

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

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Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

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