[#446 Tier 1 #5 follow-up] wasm_export_call Zig-FFI smoke-test #501

Context

Closed #455 shipped via PR #467 (Deno-ESM wasm_export_call + WasmValue) with the existing JS-side smoke-test (tests/codegen-deno/wasm_call.{affine,harness.mjs}) exercising the Deno-ESM path.

Per the owner scope breakdown, a Zig-FFI-side smoke-test was deferred to a follow-up:

Test: smoke-test through the Zig FFI

This issue tracks that. It is the test counterpart to the sister "Zig FFI implementation for wasm_export_call dispatch" follow-up — neither lands without the other.

Scope

An integration test (or just recipe) that:

1. Builds the Zig-side wasm_export_call dispatcher (from the sister implementation follow-up).
2. Compiles an AffineScript program that calls wasm_export_call via the linear-memory wasm backend (NOT the Deno-ESM backend).
3. Wires the Zig-dispatcher into the wasm instance's env import object.
4. Runs the wasm + asserts the round-trip for at least one of each WasmValue kind (i32 / i64 / f32 / f64).

Acceptance

• New test file under tests/ (or under a Zig-FFI-aware test driver — the existing tree convention will dictate).
• Demonstrates the Zig dispatcher satisfies the env.wasm_export_call import contract under the linear-memory wasm backend.
• Passes in CI under the same job that runs the existing wasm codegen tests.
• Documented as the "Zig FFI" half of the Tier 1 ci: Bump actions/github-script from 7.0.1 to 8.0.0 #5 acceptance gate in STDLIB-EXTERN-AUDIT.adoc.

Refs

• Closed kickoff: [#446 Tier 1 #5] WASM-exports calling pattern (recommended kickoff) #455
• Shipped Deno-ESM surface: PR feat(stdlib): WasmValue + wasm_export_call typed wasm-exports binding (closes #455) #467
• Sister Zig-FFI implementation follow-up: (must merge first)
• Existing Deno-ESM harness for symmetry: tests/codegen-deno/wasm_call.{affine,harness.mjs}
• Umbrella: [campaign] AffineScript top-50 framework bindings roadmap (UMBRELLA) #446 (Tier 1 — idaptik blockers)
• Tier sub-issue: [#446 STEP 2] Tier 1 — idaptik blockers (10 bindings) #450