chore: add missing npm engine constraint to stats/base/dists/uniform/ctor

Adds `"npm": ">2.7.0"` to `engines` in `package.json` so `ctor` matches the engine convention used by the other 13 sibling packages in `@stdlib/stats/base/dists/uniform` (93% conformance). The `ctor` package legitimately omits native-addon infrastructure (no `src/`, `include/`, `binding.gyp`, `manifest.json`, `lib/native.js`) because it is a constructor class; the npm engine constraint is unrelated to native bindings.

Author: claude

lib/node_modules/@stdlib/stats/base/dists/uniform/ctor/package.json

@@ -34,7 +34,8 @@
   "dependencies": {},
   "devDependencies": {},
   "engines": {
-    "node": ">=0.10.0"
+    "node": ">=0.10.0",
+    "npm": ">2.7.0"
   },
   "os": [
     "aix",