fix(build): resolve Next.js build failures from invalid route exports

- Extract detectAuthAnomalies + THRESHOLDS from route.ts to detect.ts
  (Next.js rejects non-standard exports from route files)
- Add explicit RenderResult return type to test-utils customRender
- Skip ESLint during next build (runs separately via pnpm lint)
- Revert test file exclusions from tsconfig (breaks eslint parser)
- Update route.test.ts imports to match new file structure

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/test-utils.tsx

@@ -1,5 +1,5 @@
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
-import { render, type RenderOptions } from "@testing-library/react";
+import { render, type RenderOptions, type RenderResult } from "@testing-library/react";
 import type { ReactElement } from "react";
 
 function createTestQueryClient() {
@@ -16,7 +16,7 @@ function TestProviders({ children }: { children: React.ReactNode }) {
   return <QueryClientProvider client={queryClient}>{children}</QueryClientProvider>;
 }
 
-function customRender(ui: ReactElement, options?: Omit<RenderOptions, "wrapper">) {
+function customRender(ui: ReactElement, options?: Omit<RenderOptions, "wrapper">): RenderResult {
   return render(ui, { wrapper: TestProviders, ...options });
 }