fix(0112): out-of-range int literals error instead of silently wrapping

checkIntLiteralFits range-checks a literal against its integer target
(builtins + custom widths via intLiteralRange; width-64 types skip —
every representable literal is a legal bit pattern there) and diagnoses
with the type's range and an xx/cast hint. Wired into the .int_literal
arm (covers decls, assignments, call args, struct-literal fields),
lowerStructConstant, and globalInitValue.

A negated literal now folds to a single constant so -128 range-checks
as -128 rather than as an out-of-range +128 intermediate. An explicit
xx operand skips the check — truncation stays available on request
(cast(T) was already exempt: its value arg lowers without the target).

examples/0300-closures-lambda.sx pinned 133 wrapping to -3 through an
s3 param — the exact class this outlaws; updated to a fitting value.

Found during the fix and filed separately: issue 0113 (negated-literal
global initializers rejected as non-constant; pre-existing).

Regressions: examples/1156-diagnostics-int-literal-out-of-range.sx,
examples/0174-types-int-literal-boundaries.sx.

issues/0112-int-literal-out-of-range-silent-wrap.md

@@ -1,3 +1,35 @@
+# RESOLVED — 0112: out-of-range int literal silently wraps into a narrower annotated target
+
+**Root cause:** the `.int_literal` arm adopted an integer `target_type` with no
+fits-check, truncating at emission width; `globalInitValue` serialized literal
+global initializers raw the same way.
+
+**Fix:** `Lowering.checkIntLiteralFits` (src/ir/lower.zig) range-checks a
+literal against its integer target (`intLiteralRange`: builtins + custom
+widths; width-64 types skip — every representable literal is legal there) and
+diagnoses `integer literal N does not fit in T (range lo..hi) — use an
+explicit `xx` / `cast` to truncate`. Wired into the `.int_literal` arm,
+`lowerStructConstant`, and `globalInitValue`. A negated literal now folds to
+one constant (`-128` checks as -128, not as an out-of-range +128
+intermediate), and an explicit `xx` operand skips the check
+(`suppress_int_fit_check`) — truncation stays available on request;
+`cast(T)` was already exempt (its value arg lowers without the target).
+Coverage via the shared arm: decls, assignments, call args, struct-literal
+fields, struct constants, globals.
+
+**Behavior change:** `examples/0300-closures-lambda.sx` passed `133` to an
+`s3` param and pinned the wrapped `-3`; updated to a fitting value.
+
+**Regression tests:** `examples/1156-diagnostics-int-literal-out-of-range.sx`
+(both faces diagnosed in one run) and
+`examples/0174-types-int-literal-boundaries.sx` (extreme in-range values,
+width-64 types, `xx`/`cast` escapes, call args).
+
+**Found during the fix:** negated-literal GLOBAL initializers (`g : s64 = -1;`)
+are rejected as non-constant — pre-existing gap, filed as issue 0113.
+
+---
+
 # 0112 — out-of-range int literal silently wraps into a narrower annotated target
 
 **Symptom.** An integer literal that does not fit its explicitly-annotated