fix: JS reliability bugs (SonarCloud S1764, S9383, S4275)

- scriptui.js: replace the self-comparison NaN check (o.max === o.max) with
  the explicit Number.isNaN(o.max) (S1764).
- sw.js: mark the fire-and-forget cache.put() with void and a .catch() so the
  promise rejection is handled (S9383).
- prelude.js: return __err(...) from the activeCamera getter so every path
  yields a value (S4275); __err always throws, so behavior is unchanged.

apps/effectcraft-web/web/sw.js

@@ -38,7 +38,7 @@ self.addEventListener("fetch", (event) => {
       const hit = await cache.match(key, { ignoreSearch: req.mode === "navigate" });
       if (hit) return hit;
       const res = await fetch(req);
-      if (res.ok && res.type === "basic") cache.put(req, res.clone());
+      if (res.ok && res.type === "basic") void cache.put(req, res.clone()).catch(() => {});
       return res;
     })(),
   );