wasm32 ReleaseSafe build fails: 64-bit atomics in io_helper/preview_shm not supported on wasm32

[apotema]

wasm32-emscripten ReleaseSafe builds of a generated game fail: std/atomic.zig:53: error: expected 32-bit integer type or smaller; found 64-bit integer type (compile lib game ReleaseSafe wasm32-emscripten). wasm32 baseline does not support 64-bit atomics. Sources in engine code compiled for wasm: io_helper.zig:26 std.atomic.Mutex (since #590, ~May 26), and preview_shm.zig:607/676 + preview_iosurface.zig:361 (@atomicStore/@atomicLoad(u64,...)). Pre-existing (predates the controller work); surfaced by labelle-cli Docker Build Test -> "Test --docker WASM build". Fix: use 32-bit atomics / a wasm-safe lock, or guard these for wasm32. Found during gamepad cleanup but independent of it.

[apotema]

Root cause pinned down (my original guess at io_helper/preview_shm was wrong): the actual first error is the zig-ecs adapter — ecs/zig-ecs/src/adapter.zig:58 calls next_instance_id.fetchAdd(1, .monotonic) on a std.atomic.Value(u64) (referenced inline from std/atomic.zig:53). wasm32 baseline has no 64-bit atomics. Fixed in labelle-assembler by switching instance_id (+ counter + threadlocal cache id) to u32. (io_helper std.atomic.Mutex actually compiles fine for wasm32 — verified — so it was a red herring.)

[apotema]

Fixed by labelle-toolkit/labelle-assembler#264 (ECS adapter instance_id u64 -> u32). Verified end-to-end: the labelle-cli Docker WASM build re-ran green against the fixed adapter, and cli#247 merged. No further 64-bit atomic surfaced in the wasm path.