Add support for DOCX and TXT résumé formats

[saviobatista]

Business Value
Supporting additional file formats increases accessibility for users who may not have their résumé in PDF format.

Description
Add the ability to upload and process .docx and .txt files in addition to PDF. Ensure they integrate into the same parsing pipeline and fallback to AI when needed.

Technical Details

• Extend file upload validation to allow .docx and .txt
• Use mammoth for .docx to extract plain text
• Use basic file reader for .txt files
• Normalize inputs into the same text-processing pipeline as PDF

Acceptance Criteria

• Users can upload .docx and .txt formats
• Text is extracted and processed equivalently to PDF
• All parsing and AI logic applies to these formats
• Invalid or unsupported formats are rejected gracefully