tests: add comprehensive unit tests for linktree module (fixes #300)

[Sid0004]

Summary

This PR adds comprehensive unit tests for the torbot.modules.linktree module as requested in issue #300.

Changes

• ✅ Added 18 tests for LinkTree and LinkNode classes
  • Tree building with depth limits
  • Duplicate URL handling
  • File I/O (JSON and text output)
  • Contact extraction (emails, phone numbers)
  • HTTP status code handling
• ✅ Added 11 edge-case tests for parsing helpers
  • parse_hostname(), parse_links(), parse_emails(), parse_phone_numbers()
  • Empty inputs, invalid data, malformed URLs
• ✅ Added test infrastructure
  • tests/conftest.py - test-time shim for NLP classifier (avoids numpy dependency in tests)
  • run_tests.py - helper script for running tests without package installation

Coverage

All tests pass (29/29). This PR covers:

• ✅ Parsing edge cases (empty inputs, invalid formats, duplicates)
• ✅ Tree construction and navigation
• ✅ Depth-limited recursion
• ✅ Contact extraction integration
• ✅ File persistence (JSON and text)
• ✅ Error handling for malformed data

Fixes #300

Test Results

[Sid0004]

Hi maintainers! 👋

I've added comprehensive unit tests for the linktree module as requested in #300. All 29 tests pass locally.

Quick summary:

• 18 tests for LinkTree/LinkNode (tree building, depth limits, duplicates, file I/O)
• 11 edge-case tests for parsing helpers
• Added test infrastructure to run without heavy ML dependencies

Happy to make any changes if needed. Thanks for reviewing!

[KingAkeem]

pytest build failed

[Sid0004]

Changes: Removed the errant line that was causing NameError: name 'LinkTree' is not defined

[Sid0004]

! I wanted to kindly ask if you could please add the hacktoberfest-accepted label to my pull request in this repo .
I really appreciate your time and the opportunity to contribute — thank you again for reviewing my work!

[KingAkeem]

Code LGTM and runs successfully, great work

[Sid0004]

Could you please mark this PR as “hacktoberfest-accepted” so it counts toward the event? Thank you!

[Sid0004]

Thank you again for merging my PR! Really appreciate your time and support.

[KingAkeem]

You're welcome and will do, thank you for the contribution. Feel free to tackle anything else that you'd like.