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.

examples/1156-diagnostics-int-literal-out-of-range.sx

@@ -0,0 +1,12 @@
+// An integer literal that does not fit its integer target type is a
+// compile error (no silent wrap): both faces diagnosed in one run.
+// Regression (issue 0112): `x : s8 = 300` bound 44, `y : u8 = 256` bound 0.
+
+#import "modules/std.sx";
+
+main :: () {
+    x : s8 = 300;
+    print("x: {}\n", x);
+    y : u8 = 256;
+    print("y: {}\n", y);
+}