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.
Migrate lowerAssignment's `.field_access` target onto the shared
`fieldLvaluePtr` resolver, deleting its duplicated union / promoted /
tuple / vector / struct walk. All three lvalue field-store sites —
single-assign, address-of (lowerExprAsPtr), and multi-assign
(lowerMultiAssign) — now resolve through the one resolver, removing the
issue-0083 two-resolver divergence.
Fold vector-lane resolution into `fieldLvaluePtr` (reusing
vectorLaneIndex) so the single resolver covers struct fields, union
direct fields, promoted anonymous-struct union members, tuple elements,
and vector lanes — null only on a genuine miss, which every caller turns
into the read path's `emitFieldError` diagnostic.
`fieldLvaluePtr` now types every field GEP `*field_ty` (the convention
the single-assign path always used), not the bare field value type:
emitStore unwraps one pointer level to find the stored value's type.
The earlier lowerExprAsPtr / lowerMultiAssign walks typed the GEP with
the bare field type, so a field whose own type is a pointer-to-aggregate
(`*Pair`, a two-pointer struct) made emitStore unwrap to the aggregate
and coerceArg's closure auto-promotion store a 16-byte `{ptr,null}`
struct over the 8-byte slot, clobbering the neighbouring field.
Consolidating onto the one `*field_ty` resolver preserves single-assign
and fixes that pre-existing multi-assign / address-of clobber.
The types.zig `.unresolved` tripwire is untouched; no `.s64` / `.void` /
`.unresolved` default remains.
Regression: examples/0167-types-ptr-to-aggregate-field-store.sx (a
`*Pair` field stored via all three lvalue sites leaves the neighbour
intact) + a lowering unit test asserting the `*field_ty` GEP convention.
