fix: 2026-08-10 audit follow-up — count/flag/link accuracy, semantic passages

[silversurfer562]

Summary

Accuracy fixes from the 2026-08-10 full library audit: three numeric-claim false-positive classes stopped, two silent false-negative classes closed, markdown link titles handled, and the semantic layer now judges against real source passages instead of the content itself. Every fix carries paired clean + hallucinated corpus cases.

Fixed

• Comma-grouped numbers are one claim — "1,234 tests" no longer extracts the "234" fragment and errors against tests=1234; grouped year-valued counts ("2,026 widgets") stay checked.
• Decimals and version components are not counts — "94.53" and the "10" in "Python 3.10" are no longer claims.
• Short count-source labels are no longer silently dead — "api"/"eps" labels now match (exact word boundary), but only as a fallback when the label has no longer word, so stopwords in mixed labels ("number of tests") can't drag unrelated numbers into the source.
• Flags in single-span commands and shell fences are checked — `mytool --flag` and ```bash fences were entirely unchecked; only a flag backticked alone was seen, despite a code comment claiming otherwise. Corpus flag cases updated to the realistic single-span form.
• Markdown link titles and <angle-bracket> targets no longer break path existence checks; dead paths with titles are still flagged.
• Semantic layer judges against VerifyContext.passages (new field) instead of the content itself, which was vacuously faithful by construction; with no passages the judge is skipped with a warning. No-judge vs. protocol-mismatch warnings are now distinct messages.
• Import resolution passes the module name via argv instead of f-string interpolation into python -c (defense in depth).

Test plan

• Suite grew 83 → 99 tests; 12 new corpus cases guard each fix from both the precision and recall side (corpus gate ≥ 0.95 both).
• All five original audit repros verified fixed by direct probe; adversarial probes for stopword labels, --flag=value, console-fence help output, and year/comma interplay behave correctly.
• ruff + black clean; mutation gate runs in CI.

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