Supabase example has duplicate utils for cn.ts

[damiensedgwick]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

bunx next info
/bin/sh: yarn: command not found
/bin/sh: pnpm: command not found

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.2.0: Fri Dec  6 19:00:33 PST 2024; root:xnu-11215.61.5~2/RELEASE_ARM64_T8122
  Available memory (MB): 8192
  Available CPU cores: 8
Binaries:
  Node: 20.13.1
  npm: 10.5.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.1.0 // Latest available version is detected (15.1.0).
  eslint-config-next: N/A
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.6.3
Next.js Config:
  output: N/A

### Which example does this report relate to?

with-supabase

### What browser are you using? (if relevant)

_No response_

### How are you deploying your application? (if relevant)

_No response_

### Describe the Bug

There is duplication of code for the classNames utility. It currently exists in 2 places with this example. Both in `lib/utils.ts` and in `utils/cn.ts` when creating a new project using `bunx create-next-app -e with-supabase`.

### Expected Behavior

It should only be declared in one location.

### To Reproduce

Create a new project using `bunx create-next-app -e with-supabase` and check the 2 locations shared in the description.