Add --files-from option to read input files from a file

[kyllianaucher]

Add support for a --files-from option to read input file paths from a file.

This allows users to specify a file containing a list of files to analyze,
with support for - to read from stdin.

Implementation details:

• Additional file paths are collected before verification.
• Errors while reading are reported via printErr.
• RuntimeException is thrown if the file cannot be read.
• The existing parsing and analysis pipeline remains unchanged.

The man page has been updated accordingly.

Tested locally with:

• valid file list
• non-existent file
• stdin input (--files-from=-)
• combination with direct file arguments

Let me know if you’d like tests or changelog updates.