The token-pattern detector had 15 near-identical test methods across
`TestScanTokenPatterns` and `TestScanTokenPatternsExtended`, each
scanning a body carrying one synthetic token and asserting the reason
names the credential type.
Collapse them into a single `_TOKEN_PATTERN_CASES` table driven by
`subTest`, so adding a new token shape is a one-line row. Each case now
also asserts block severity (previously only the AWS case did).
`TestScanTokenPatternsExtended` is removed; its rows live in the table.
The non-matrix cases (clean text, location, context, reason) stay as
explicit methods. No production code change.
Closes#289
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NkwFXLFff9PYPy4wgVBJp9