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.
The trace docs predated the current formatter. Corrected against the real
output (library/modules/trace.sx to_string + examples/expected/1025-errors-
trace-format.stderr):
- error-handling.md: replace the obsolete trace example ("error trace:" /
"raised error.X" / "at func (file:line)") with the real format —
"error return trace (most recent call last):" + per-frame "func at
file:line:col" + source line + caret.
- debugger.md: drop the stale "(planned)" marker on the trace formatter
(it is implemented); the tag-name table note now cites the failable-main
reporter's "unhandled error reached main: error.X" line, not a
nonexistent "raised error.X" trace line.
