examples: Add .npmrc to Dockerfile to support custom npm configs (#72132)
### Description:
This PR continues the work started in
[#72064](https://github.com/vercel/next.js/pull/72064) (already merged)
by updating the Dockerfiles in the `examples` folder to include the
`.npmrc` file in the dependency copy command.
### Original Command:
```dockerfile
# Install dependencies based on the preferred package manager
COPY package.json yarn.lock* package-lock.json* pnpm-lock.yaml* ./
```
### Updated Command:
```dockerfile
# Install dependencies based on the preferred package manager
COPY package.json yarn.lock* package-lock.json* pnpm-lock.yaml* .npmrc* ./
```
### Reason for Change:
Including `.npmrc` allows for custom npm configurations, such as
`legacy-peer-deps=true`. Without this option, some installations can
fail due to unresolved peer dependencies, particularly for projects with
older dependencies.
This update ensures that any additional configurations specified in
`.npmrc` are applied during installation, improving Docker build
consistency and stability for projects with custom npm requirements.
### Diff:
```diff
- COPY package.json yarn.lock* package-lock.json* pnpm-lock.yaml* ./
+ COPY package.json yarn.lock* package-lock.json* pnpm-lock.yaml* .npmrc* ./
```
next.js
39c4cf9a - examples: Add .npmrc to Dockerfile to support custom npm configs (#72132)
