fix(ir): integral-float counts + range-checked value-param binds (0083)

Item 2 (Agra ruling): a compile-time INTEGRAL float (`4.0`, `N : f64 :
4.0`, `N :: 4.0`) used as an array dimension / Vector lane / generic
value-param count / `inline for` bound now folds to its integer at the
shared leaf — `program_index.floatToIntExact`, used by both the
`.float_literal` arm of `evalConstIntExpr` and `moduleConstInt`. All four
consumers route through the one evaluator, so `[4.0]s64` lays out the same
`[4]s64` uniformly; a non-integral (`4.5`) or negative value stays
rejected by the downstream `foldDimU32` gate. Pass-0 now pre-registers
float-valued module consts for forward-alias parity with int consts.

Item 1: a generic value-param bind (`Box($K: u32)`) never range-checked
the folded arg, so `Box(5_000_000_000)` compiled and ran. The bind now
range-checks against the param's declared type — a `u32` count through the
shared `foldDimU32` gate (making program_index's "single u32 gate for
value-param counts" doc true), any other integer type through the new
`program_index.intTypeRange` — and emits a clean "value N does not fit in
u32 parameter K" otherwise. The declared type is threaded via a new
`TemplateParam.value_type`.

Regressions: examples 0145 (integral-float array dim), 1504 (Vector lane),
0611 (inline-for bound), 0209 (value-param integral-float), 1132
(non-integral float dim rejected), 1133 (negative float dim rejected),
1134 (oversized u32 value-param rejected) + program_index float-fold unit
tests. Gate: zig build, zig build test, 406/0 run_examples.

examples/1504-vectors-integral-float-lane.sx

@@ -0,0 +1,12 @@
+// A Vector lane count accepts an integral float constant — `L : f64 : 4.0` lays
+// out the same `Vector(4, f32)` as the literal `4`. The lane resolver shares the
+// const-int evaluator with the array-dim path, so the integral-float rule
+// (issue 0083 / F0.4 attempt 8, Agra ruling) applies uniformly.
+#import "modules/std.sx";
+
+L : f64 : 4.0;
+
+main :: () {
+    v : Vector(L, f32) = .[1.0, 2.0, 3.0, 4.0];
+    print("v0={} v2={} v3={}\n", v[0], v[2], v[3]);
+}