Detect Linear API keys (lin_api_...)

[omerbek]

Format: lin_api_ followed by about 40 alphanumeric characters. Verify the exact length against Linear's docs.

How to do it

1. Add ("Linear API key", r"\blin_api_[A-Za-z0-9]{40}\b") (or your verified version) to SECRET_PATTERNS in repodx.py.
2. Add "lin_api_" to CANDIDATE_LITERALS.
3. Add the key to SecretScanTests.test_detects_provider_keys in tests/test_repodx.py, built with fake(...) so no literal key is committed.
4. Run python3 -m unittest discover and python3 repodx.py . (must stay 100/100).

Comment here to claim it. One issue per person, so more people can join. See CONTRIBUTING.md. Never paste a real key.