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.
Codex review of 95895a3 found 1051 reached neither lambda arm it claimed to
pin: the lambda arrived only as a var_decl initializer, which routes through
checkCleanupNode's `.var_decl` arm -> cleanupReject(lambda) -> early-return
(a lambda literal is not failable), so the `.lambda` stop never ran; and its
accepted-direction `if !err` guard would still pass with flowExpr's lambda
recursion removed.
Scaffolding-only fix (no compiler change):
- 1051: add a bare lambda STATEMENT `() -> !E { failing(); };` in the cleanup
body so checkCleanupNode sees a `.lambda` node directly and stops (the bare
failable inside is accepted; were the arm to recurse it would reject like
1052). Output byte-identical — only the .sx gained the statement.
- 1053-errors-nested-lambda-liveness-reject (exit 1): an E1.8 value-slot read
inside a never-called nested lambda, rejected only because flowExpr recurses
via `.lambda => analyzeFnBody`. Remove that arm and the diagnostic vanishes
-> suite fails. This is the discriminating negative 1051 lacked.
Gate: zig build test, bash tests/run_examples.sh -> 361/0.
