fix(compiler): preserve declared type of const references

A const reference lowered to `val(itoa(g.a.ival), "int")` in emit_call.ludic —
the initializer's raw integer bits, hardcoded as `int`. For a fixed const like
`const X: fixed = 10.0` that yielded the Q16.16 bits (655360) typed as int, so
every fixed comparison/arithmetic against it silently broke (it caused an
infinite loop in runtime/native/numeric.ludic, previously worked around with
inline literals).

Fix: a const reference now emits its initializer expression via emit_expr(g.a),
which carries the initializer's real type (E_FLOAT->fixed, E_BOOL->bool,
E_STR->string) and even handles computed initializers. Every existing const is
an int literal, for which this is byte-identical to the old immediate — the
C-free bootstrap fixpoint and all golden renders are unchanged.

- selfhost/tests/const.ludic + sh_case pin fixed/int/bool const behaviour.
- runtime/native/numeric.ludic restored to named fixed consts (HUGE_TEN etc.),
  which the workaround had inlined; the numeric example (20 assertions) still
  passes, validating the fix under runtime splice.

All suites green: x selfhost-test 31/31 (fixpoint holds, goldens byte-identical),
x test 85/85, x test-tools 30/30.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

changes/fix-fixed-const-type.md

@@ -0,0 +1,11 @@
+bump: patch
+type: fix
+**`const` of a non-int type is no longer miscompiled.** A `const` reference used
+to lower to its initializer's raw integer bits hardcoded as type `int`, so a
+`const X: fixed = 10.0` compared and computed as the raw Q16.16 value `655360`
+instead of `10.0` — silently corrupting fixed-point math (and, in one case, spinning
+an infinite loop). A const reference now emits its initializer expression with that
+expression's real type, so `fixed` / `bool` / `string` consts behave correctly (and
+computed const initializers work too). Every existing const is an `int` literal, for
+which the lowering is byte-identical, so the bootstrap fixpoint and all golden
+renders are unchanged. Covered by selfhost/tests/const.ludic.