improve filename sanitization for hash routes

[Awsum-Al]

This enhancement modifies the filename sanitization process to handle hash-based routing more elegantly. By removing leading underscores from sanitized values, we create cleaner and more readable filenames for Single Page Applications using hash-based navigation.

Changes:

• Updated getFileOutputPath sanitization to remove leading underscores
• Maintains all existing functionality while improving readability
• Particularly beneficial for React, Vue, and other SPA frameworks
• Preserves path information without unnecessary prefixes

Example transformation: Before: _dashboard-2024_11_13.report.html After: dashboard-2024_11_13.report.html

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