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/expected/0174-types-int-literal-boundaries.exit

@@ -0,0 +1 @@
+0

examples/expected/0174-types-int-literal-boundaries.stderr

@@ -0,0 +1 @@
+

examples/expected/0174-types-int-literal-boundaries.stdout

@@ -0,0 +1 @@
+-128 127 0 255 9223372036854775807 4294967295 -32768 44 44 -5

examples/expected/1156-diagnostics-int-literal-out-of-range.exit

@@ -0,0 +1 @@
+1

examples/expected/1156-diagnostics-int-literal-out-of-range.stderr

@@ -0,0 +1,11 @@
+error: integer literal 300 does not fit in s8 (range -128..127) — use an explicit `xx` / `cast` to truncate
+  --> examples/1156-diagnostics-int-literal-out-of-range.sx:8:14
+   |
+ 8 |     x : s8 = 300;
+   |              ^^^
+
+error: integer literal 256 does not fit in u8 (range 0..255) — use an explicit `xx` / `cast` to truncate
+  --> examples/1156-diagnostics-int-literal-out-of-range.sx:10:14
+   |
+10 |     y : u8 = 256;
+   |              ^^^

examples/expected/1156-diagnostics-int-literal-out-of-range.stdout

@@ -0,0 +1 @@
+