chore: enforce zero-warning toolchain

- Enable noUnusedLocals/noUnusedParameters in tsconfig (unused code = error)
- Remove unused React import in scroll-area (caught by strict unused checks)
- Pin NODE_ENV=development for dev script (box shell leaks NODE_ENV=production,
  which made next dev emit a non-standard-env warning)

components/ui/scroll-area.tsx

@@ -1,6 +1,5 @@
 "use client";
 
-import * as React from "react";
 import { ScrollArea as ScrollAreaPrimitive } from "@base-ui/react/scroll-area";
 import { cn } from "cn";