feat(lang): float numeric-limit accessors — examples, unit tests, docs [NL.2]

Finish NL.2 on top of the WIP compiler impl (2e9e4fe): f32/f64 expose
.min/.max plus the float-only .epsilon/.min_positive/.true_min/.inf/.nan,
folded via the shared lowerNumericLimit intercept + builder.constFloat.

- examples/0159: pins every f32/f64 accessor by untagged-union bit
  reinterpret against exact IEEE-754 hex (true_min read before any
  arithmetic — FTZ/DAZ), plus the defining-property checks
  ((1+eps)!=1 / (1+eps/2)==1, inf>max, min==-max, true_min<min_positive,
  true_min>0, nan!=nan).
- examples/0160: float-only accessor on an int (s32.epsilon/u8.inf/
  s64.true_min) and any accessor on a non-numeric type compile-error
  cleanly (exit 1, pinned stderr).
- type_resolver.test.zig: floatLimitFor bit-pattern + property tests for
  f32/f64, isLimitField coverage, null for non-float/non-limit fields.
- specs.md Numeric Limits: float accessors + the min=-max / min_positive=
  smallest-normal / epsilon=ULP-of-1.0 / true_min=smallest-subnormal
  clarifications, with the mandatory FTZ/DAZ flush-to-zero caveat.
  readme.md overview updated.

readme.md

@@ -90,7 +90,13 @@ Options:
 a compile-time constant of that type: `s64.max` → `9223372036854775807`,
 `u8.min` → `0`, `s3.max` → `3`. It works for every width `s1`..`s64` / `u1`..`u64`
 plus `usize`/`isize`, and is usable anywhere a constant of that type is — including
-array dimensions (`[u8.max]T` is a 255-element array).
+array dimensions (`[u8.max]T` is a 255-element array). The float types `f32`/`f64`
+expose `.min` / `.max` too (with `.min` = most-negative finite = `-max`, **not**
+C's `DBL_MIN`) plus the float-only `.epsilon` (ULP of 1.0, not C#'s denormal
+`Epsilon`), `.min_positive` (smallest normal = C `DBL_MIN`), `.true_min` (smallest
+subnormal — beware flush-to-zero CPU modes), `.inf`, and `.nan`. A float-only
+accessor on an integer (`s32.epsilon`), or any accessor on a non-numeric type, is
+a clean compile error. See `specs.md` → Numeric Limits.
 
 ### Declarations