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.
E4's pack-fn source-pin was incomplete: an imported pack function's
fixed-prefix (non-pack) parameter types were resolved in the CALLER's
module, so a param whose type is bare-visible only in the pack fn's own
module was wrongly rejected with "type 'X' is not visible" — even though
the equivalent plain fn (typed via the source-pinned call-arg path) ran
fine.
Two sites in the pack-mono path re-resolved the fixed-prefix param type
in the caller's context:
- lowerPackFnCall: the call-site arg-typing pass (to contextually type
the arg from its param) — fires first.
- monomorphizePackFn: the body parameter binding, after the caller
source was restored from the signature build.
Both now resolve via resolveParamTypeInSource(fd.body.source_file, &p),
pinning to the pack fn's defining module — matching the already-pinned
signature build, the body lowering, and the cross-module call-arg typing
sites. The call-site arg itself is still lowered AFTER, in the caller's
context (issue 0106).
Regression: examples/0544-packs-imported-pack-fn-fixed-param-source-pin
(main -> lib -> dep; `Needs` two flat hops away, never named in main).
Fails pre-fix with "type 'Needs' is not visible"; passes after. A control
plain fn in the same lib already ran, isolating the pack-mono path.
