fix(noise): WASM rng cfg gates check wasm64, so wasm32 browser builds still panic

[iWhatty]

The bug

add_noise_rand and pink_noise panic with RuntimeError: unreachable in every browser WASM build, despite the [WASM SUPPORT IS AVAILABLE] docstrings.

The js_sys::Math::random workaround introduced in #162 is gated at every use site on:

#[cfg(all(target_arch = "wasm64", not(target_os = "wasi")))]

Browser builds target wasm32-unknown-unknown, which fails that condition - so they compile the rand::thread_rng() branch instead, and thread_rng has no entropy source on wasm32-unknown-unknown, panicking on first call. (The use js_sys::Math::random import at the top of the file is already gated on target_family = "wasm", which is why the import compiles but goes unused on wasm32.)

The fix

Switch the seven use-site gates from target_arch = "wasm64" to target_family = "wasm", matching the existing import gate. wasm32 + wasm64 both take the Math.random path; native keeps rand::thread_rng().

Verification

• cargo check clean on wasm32-unknown-unknown and native (aarch64-apple-darwin).
• Runtime, via wasm-pack build --target nodejs of master vs this branch:

master:      add_noise_rand -> RuntimeError: unreachable
this branch: add_noise_rand + pink_noise run and mutate pixels

Context: we hit this in production on Photon Lab (a browser playground built on photon-rs) and had to cut the noise functions from the UI; this one-line-class fix would let us (and anyone on @silvia-odwyer/photon) re-enable them once released.

Thanks for photon - it's a joy to build on.

[silvia-odwyer]

@iWhatty Thank you very much for your PR and this fix, much appreciated! Everything looks good to me, so going to merge this now ✅

I also checked out Photon Lab, I'm delighted that you decided to use Photon for this :) Going to add a link to this web app in the Readme also so others might see it and try it out 🚀