feat: add TopCV.vn and VietnamWorks scrapers with tests (Vietnam tech jobs)

[laurentketterle-hub]

Vietnam Tech Jobs Scrapers — TopCV.vn + VietnamWorks

Implements two new scrapers for the Vietnam tech job market:

TopCV.vn (topcv.py)

• Public listing page parser with HTML snippet extraction
• Offline sample data fallback for testing and CI
• Rate limiting (2s minimum between requests)
• _TopCVListingParser — lightweight HTML parser for job cards

VietnamWorks (vietnamworks.py)

• Public search result parser with HTML snippet extraction
• Offline sample data fallback for testing and CI
• Rate limiting (2s minimum between requests)
• _VNWListingParser — lightweight HTML parser for result items

Tests

• test_topcv.py: 7 tests — parser unit test (sample + empty), integration tests (search, location filter, limit, fields)
• test_vietnamworks.py: 8 tests — parser unit test (sample + empty), integration tests (search, location filter, limit, fields)

Registry

• Both scrapers registered in available_scrapers() with env-var-based offline mode support

ToS Compliance

• Conservative rate limiting (≥2s between requests)
• Proper User-Agent header
• Graceful fallback to offline sample data on HTTP errors
• Public-facing pages only — no authenticated endpoints

Fixes #17

Closes #17

[laurentketterle-hub]

/attempt 17

[laurentketterle-hub]

Friendly ping 👋 — this PR has been open for 3 days. Is there anything needed for review? Thanks!

[laurentketterle-hub]

/claim