feat(types): Huge + Angle + Percent polish numeric types (#55)

Types phase 5 (polish). A splice-on-demand numeric runtime
(runtime/native/numeric.ludic, built on the inline Math.* trig) behind three
namespaces:

- Huge.* — idle big numbers (normalized mantissa x 10^exponent): from/add/
  sub/mul/neg/cmp/sign/mantissa/exp/str (scientific 1.23e45). Display-scale,
  not lockstep-exact (BigInt/Decimal for exactness).
- Angle.* — auto-wrapping radians: from_degrees/to_degrees/wrap/sin/cos/add/
  diff (shortest signed rotation)/lerp (shortest arc).
- Percent.* — clamped [0,1]: clamp/of/lerp/apply.

Remaining phase-5 items are already covered (duration=Duration.*,
rune=Unicode.*, i64=long) or need a type-checking pass (handle, typed name,
other sized ints) — tracked for later.

Wired: parser splice trigger (g_uses_numeric), emit_call dispatch, reseeded
seed, a self-asserting example (examples/library/numeric.ludic + feat_case),
per-symbol docs + inventory. All suites green incl. golden renders byte-
identical and the bootstrap fixpoint.

NOTE: fixed `const`s lower to raw-int-typed values (emit_call N_CONST), which
breaks fixed comparisons — the runtime uses inline fixed literals instead.

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

docs/language/percent/_section.md

@@ -0,0 +1,7 @@
+---
+id: percent
+title: Percent
+order: 16
+---
+
+A value clamped to <code>[0, 1]</code> — health fractions, volumes, and the <code>t</code> of an interpolation, without stray values slipping below 0 or above 1. <code>Percent.clamp</code> pins any <code>fixed</code> into range; <code>Percent.of</code> forms a clamped ratio <code>num / den</code>; <code>Percent.lerp</code> interpolates <code>a..b</code> by a clamped <code>t</code>; and <code>Percent.apply</code> scales a value by a clamped fraction. Every operation is deterministic fixed-point. Arguments are positional. Spliced in only when a program mentions <code>Percent.*</code>.