add comma separated support for -l option

[dogancanbakir]

closes #878

Summary by CodeRabbit

• New Features

  • Support comma-separated host values with the --list / -l flag (file or stdin still supported).

• Bug Fixes

  • Enforce mutual exclusivity of stdin across domains, wordlist, and hosts with clearer errors.
  • In stream mode, explicitly disallow hosts input.
  • Improve stdin handling and temporary-file cleanup to avoid unnecessary copies and ignore cleanup errors.

• Tests

  • Added tests for hosts input formats (file, stdin, inline, comma-separated) and related error cases.

• Documentation

  • Updated --list / -l flag description to mention comma-separated input.