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.
Three adjacent cells of the shared count surface still diverged from the
rest; all now route through the same leaf+fold+narrow+diagnose path.
1. Aliased integer constraint bypassed the value-param range gate — only
builtin constraint names matched intTypeRange, so Box(5_000_000_000)
with `$K: Count` (Count :: u32) compiled and bound a truncated value.
resolveValueParamArg (shared by both the struct AND type-fn binder) now
resolves the constraint to its underlying builtin via
canonicalIntConstraintName (Count -> u32, Small -> s8) before
range-checking, so an aliased integer constraint behaves exactly like
the builtin it names.
2. A named const with an expression RHS (M :: 2; N :: M + 1) did not fold
as a count — moduleConstInt read only a literal RHS node. It now folds
every const's RHS through the shared evalConstIntExpr, cycle-guarded
(mutual / self cycles fold to null, not a stack overflow), and pass-0
pre-registers expression-RHS consts. N :: M + 1 == 3 at every consumer:
dim (direct + alias), Vector lane, value-param (struct + type-fn),
inline for.
3. Stateful resolveArrayLen still fabricated length 0 after a failed fold;
it now returns null -> the .unresolved sentinel (no fabrication). The
binding's lowering never reaches sizeOf (alloca defers it; hasErrors
aborts first) and a field access on an already-diagnosed .unresolved
value is poison-suppressed (emitFieldError), so a failed-fold dim emits
ONE clean diagnostic with no panic.
Regressions: examples/0146 (full positive matrix — every consumer x leaf
form), 1135 (aliased u32 + s8 overflow), 1136 (direct non-const dim halts
cleanly). The cascade cleanup also tightened 1502/1503 to one diagnostic.
Unit test added for moduleConstInt expression-folding + cycle detection.
