Gap: Int32Array/Float64Array(n) constructor sets length=0; Uint8ClampedArray doesn't clamp

[proggeramlug]

Summary

test_gap_typed_arrays.ts surfaces three related bugs in typed-array constructors + bounded stores.

Repro

const i1 = new Int32Array(3);
i1[0] = -100; i1[1] = 0; i1[2] = 2147483647;
console.log(i1.length);                    // expected 3, perry: 0

const f1 = new Float64Array(3);
console.log(f1.length);                    // expected 3, perry: 0

const clamped = new Uint8ClampedArray(3);
clamped[0] = 300;  // expected 255 (clamped)
clamped[1] = -10;  // expected 0 (clamped)
clamped[2] = 128;
console.log(clamped[0], clamped[1], clamped[2]);
// expected: 255 0 128
// perry:    300 -10 128

Scope

• new Int32Array(n) / new Float64Array(n) must allocate with length = n and zero-fill (currently appears to default to empty)
• new Uint8ClampedArray(n) stores: store(i, v) must clamp via Math.min(255, Math.max(0, Math.round(v))) — NOT truncate-wrap like Uint8Array. Perry is storing raw values.

Impact

One of six currently-failing gap tests (baseline 22/28). Touches typed-array allocation + the per-element store path in the runtime's typed_array module. Likely straightforward if the backing implementation already exists; just the length field and clamping arithmetic.