AOT: instantiate .wasm ES module imports (import * as wasm from './x.wasm') and expose its exports #5234

Context: real apps import compiled WebAssembly as ESM modules (wasm-bindgen "bundler"/"web" target). e.g. opencode pulls @silvia-odwyer/photon-node, whose photon_rs_bg.js does import * as wasm from "./photon_rs_bg.wasm" and calls wasm.someExport(...). The import is expected to yield the instantiated module's named exports.

Goal

Support import * as wasm from "./x.wasm" (and named/default forms) by instantiating the WebAssembly module at module-init and exposing its exports as the module's named exports, wired to the importing JS glue's imports object (wasm-bindgen creates a circular glue↔wasm import relationship). perry already has a runtime WASM host — crates/perry-runtime/src/webassembly.rs (WebAssembly.instantiate(bytes) works via perry_wasm_host_*) — to build on.

Self-contained repro

Minimal module exporting add(i32,i32)->i32. Create add.wasm from this base64, then main.ts:

echo 'AGFzbQEAAAABBwFgAn9/AX8DAgEABwcBA2FkZAAACgkBBwAgACABags=' | base64 -d > add.wasm

// main.ts
import * as wasm from "./add.wasm";
console.log(wasm.add(2, 3));   // expected: 5

Node (with a wasm-ESM loader) and bundlers print 5. perry today fails earlier — see # (it currently can't even read the .wasm); after deferral it would throw-on-use. This issue is the real integration that makes wasm.add(2,3) return 5.

Scope notes

• Instantiation at module-init; named exports surfaced (functions, and memory/global/table as appropriate).
• The wasm imports object: for a bare .wasm with no imports (like the repro) it's empty; for wasm-bindgen, the glue provides imports — handle the circular case (glue imports wasm exports; wasm imports glue functions).
• Companion to the cheaper deferral (#), which keeps the build moving until this lands.