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/0209-generics-value-param-integral-float.sx

@@ -0,0 +1,19 @@
+// A generic value parameter (`$K: u32`) binds a literal (`Vec(3, s64)`) and an
+// integral-float named const (`Vec(L, s64)` with `L : f64 : 4.0`) to the same
+// integer a plain `4` would — the value-param arg folds through the shared
+// const-int evaluator, so the integral-float rule (F0.4 attempt 8, Agra ruling)
+// reaches value params too. The folded value is the array length `[K]s64`.
+//
+// The bind is range-checked against the declared `u32` (an out-of-range arg is a
+// clean compile error — see 1134); a valid in-range value binds normally.
+#import "modules/std.sx";
+
+Vec :: struct ($K: u32, $T: Type) { data: [K]T; }
+
+L : f64 : 4.0;
+
+main :: () {
+    a : Vec(3, s64) = ---;       // literal value param
+    b : Vec(L, s64) = ---;       // integral-float named-const value param → 4
+    print("a.len={} b.len={}\n", a.data.len, b.data.len);   // 3 and 4
+}