`@symbol("rt_abort")` and similar attr arg literals (N_STRLIT inside
N_ATTR.list) never reach the post-order exprtype dispatch because the
top-level dispatch in checkfile pass-2 only enters per-decl via d.lhs
and d.body — d.attr was an oversight. Add a one-line resolvewalk
descent before the kind dispatch, mirroring resolvewalk L405 which
already descends n.attr on inner nodes.
Discovered while landing the A.6.2.1 assertion: the unstamped
N_STRLIT inside `@symbol("...")` would trip the assertion on every
selfhost source (lib/os pulls these in transitively). Fix lands as
its own prep commit so the next session can start clean on the
A.6.2.1 main work (bail-discipline refactor per Drew's 5-lite, then
δ+γ stamp completion).
A.6.2 status: 0a-g landed; 0b-pre N_TPARAM landed; assertion enable
(A.6.2.1e) deferred behind 5-lite + per-bail closure work — see
PLAN.md and tasks #20-#25.
`make sizelint` clean. `make test-unit` green; full `make test`
batched per option B (next session).
Hojun-Cho
6c70b46d5f