Newer scoped Dropbox short-lived tokens (sl.u.…) can be ~1.5KB. The scanning
engine only passes a keyword-centered window of the chunk (512 bytes by default)
to FromData, so these tokens were truncated before the regex saw them, producing
an invalid token that always verified as false.
Implement detectors.MaxSecretSizeProvider on the Dropbox scanner so the engine
widens its window to fit the full token. Add a regression test that drives a long
token through the Aho-Corasick windowing path.
Co-authored-by: Cursor <[email protected]>
