A confuser's `expected: refuse` does not mean unanswerable. Every confuser carries
its true gold (`answer_numeric`) and is a solvable coverage target; `refuse` means
"the reader can't yet comprehend this category, so refusing is the honest outcome —
committing a WRONG value is the defect." Example: 0001 "buys a toy for 30 coins …
how many left?" is plain 50-30=20; it is refuse only because today's reader takes
`buys` as a gain.
Adds §2.1 (graduation protocol): when a general mechanism reads a category correctly
(validated on train_sample + the category, wrong=0 preserved), those cases graduate
refuse -> solve and committing their gold becomes a win. Reframes the `spurious`
verdict as "solved-before-graduation" (a graduation signal, with pair-consistency as
the genuine-reading-vs-surface-match discriminator), not automatically a defect.
Notes that no v1 category is degenerate, and how a truly-unanswerable case would be
labelled (answer_numeric: null + degenerate: true) so the two senses of "refuse"
stay distinguishable.
Spec only; no corpus/runner change (today's commits are wrong-reading, so spurious
stays flagged until a category genuinely graduates).