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.

examples/expected/0159-types-float-numeric-limits.exit

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

examples/expected/0159-types-float-numeric-limits.stderr

@@ -0,0 +1 @@
+

examples/expected/0159-types-float-numeric-limits.stdout

@@ -0,0 +1,19 @@
+f64.true_min     true
+f64.max          true
+f64.epsilon      true
+f64.min_positive true
+f64.inf          true
+f32.true_min     true
+f32.max          true
+f32.min          true
+f32.epsilon      true
+f32.min_positive true
+f32.inf          true
+(1+eps)!=1       true
+(1+eps/2)==1     true
+inf>max          true
+min==-max        true
+true_min<min_pos true
+true_min>0       true
+nan!=nan         true
+typed eps bits   true

examples/expected/0160-types-float-numeric-limits-errors.exit

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

examples/expected/0160-types-float-numeric-limits-errors.stderr

@@ -0,0 +1,35 @@
+error: type 's32' has no '.epsilon' — '.epsilon' applies only to float types (f32/f64); integer types expose only '.min'/'.max'
+  --> examples/0160-types-float-numeric-limits-errors.sx:20:10
+   |
+20 |     a := s32.epsilon;
+   |          ^^^^^^^^^^^
+
+error: type 'u8' has no '.inf' — '.inf' applies only to float types (f32/f64); integer types expose only '.min'/'.max'
+  --> examples/0160-types-float-numeric-limits-errors.sx:21:10
+   |
+21 |     b := u8.inf;
+   |          ^^^^^^
+
+error: type 's64' has no '.true_min' — '.true_min' applies only to float types (f32/f64); integer types expose only '.min'/'.max'
+  --> examples/0160-types-float-numeric-limits-errors.sx:22:10
+   |
+22 |     c := s64.true_min;
+   |          ^^^^^^^^^^^^
+
+error: type 'bool' has no '.nan' — numeric limits apply only to integer and float types
+  --> examples/0160-types-float-numeric-limits-errors.sx:23:10
+   |
+23 |     d := bool.nan;
+   |          ^^^^^^^^
+
+error: type 'string' has no '.max' — numeric limits apply only to integer and float types
+  --> examples/0160-types-float-numeric-limits-errors.sx:24:10
+   |
+24 |     e := string.max;
+   |          ^^^^^^^^^^
+
+error: field 'epsilon' not found on type 'Any'
+  --> examples/0160-types-float-numeric-limits-errors.sx:25:10
+   |
+25 |     f := MyStruct.epsilon;
+   |          ^^^^^^^^^^^^^^^^

examples/expected/0160-types-float-numeric-limits-errors.stdout

@@ -0,0 +1 @@
+