First slice of the `..$args` (variadic heterogeneous type pack)
feature. Locks in the current parser-rejection behavior so the
next commit's parser extension shows up as a behavior shift.
`examples/150-pack-parse.sx` declares `foo :: (..$args) -> s64`.
Today's parser hits `..` where it expects a parameter name
(parseParams in src/parser.zig:1558 only handles `..` inside the
type position after a colon) and emits "expected parameter name".
Expected output captures this rejection.
Per FFI cadence rule, this is the "test fails today, passes after
next commit's parser change" pair.
Pack feature plan saved at
~/.claude/plans/lets-see-options-for-merry-dijkstra.md ("Variadic
heterogeneous type packs" section). Motivates replacing the
hand-rolled per-signature `Into(Block)` impls with one generic
`impl Into(Block) for Closure(..$args) -> $R`; also unlocks
compile-time arity/type errors for `print`/`format`.
191/191 example tests + `zig build test` green.
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