Surface rename of the signed integer family: s1..s64 become i1..i64
(u1..u64, usize, isize unchanged). 'string' keeps the s-prefix arm in
name classification; width parsing moves to the i-prefix arm next to
isize.
Internal TypeId tags follow the surface (.s8/.s16/.s32/.s64 ->
.i8/.i16/.i32/.i64), as do mono-key mangle fragments (ptr_i64,
tu_i64_bool) and all display/diagnostic formatting (i{d}).
Migrated in the same sweep: stdlib + examples + issue repros + FFI C
companions (shared symbol names like ffi_id_i64), expected
stdout/stderr/ir snapshots, specs.md, readme.md, CLAUDE.md/AGENTS.md,
implementation_plan.md, docs/, issue writeups. Vendored stb_image and
historical flow state left untouched.
zig build test: 426/426; examples suite: 595/595.
A block-local type is visible only within the source that declares it. The
global `local_type_names` set was source-insensitive, so an imported generic
template's field (resolved in the template's source context, attempt-4) could
bind a type the CALLER declared block-local — silently compiling an undeclared
imported field instead of diagnosing it.
Key `local_type_names` by declaring source. The bare-TYPE gate now resolves a
local only when the query originates in the local's own source (R2 preserved);
a same-name block-local of a DIFFERENT source routes to the undeclared path so
the leak surfaces (`unknown type '...'`, exit 1) instead of escaping via the
`registered` catch-all that would otherwise resolve the globally-registered
cross-source local.
Regression: examples/0762 — imported `Bad :: struct($T) { x: T; y: LocalOnly; }`
with `LocalOnly` declared only in the caller `main` now errors in lib.sx
(fail-before on 8162170 printed `1 9` exit 0).
