Add CLI flags for selective challenge downloads and slug listing.

[Tharusha-dev]

Hi, amazing script! Here's what i added.

• Added new CLI flags:

  • --print-slugs
    Prints all available challenge slugs and exits after fetching metadata.
  • --include <file>
    Path to a file containing challenge slugs to explicitly download.
  • --exclude <file>
    Path to a file containing challenge slugs to skip.

Filtering Behavior

The download logic now follows these rules:

• If --include is provided, only challenges listed in the include file are considered.

• If --exclude is provided, challenges listed in the exclude file are skipped.

• If both flags are provided:

  • A challenge must be in the include list and
  • must not be in the exclude list.

• If --print-slugs is set, all challenge slugs are printed and the program exits without downloading.

[bolt-new-by-stackblitz]

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