Test examples with oldest supported Wasp version

[sodic]

Description

During #2482, @cprecioso noticed that our example apps don't work on older versions of Node we claim to support. This PR explores what to do about it. Discussion welcome.

The main question is: Which tests do we run on which versions of Node?
After we decide that, we can deal with how and where we specify this (I choose a repostiroy variable for now).

Type of change

• 🔧 Just code/docs improvement
• 🐞 Bug fix
• 🚀 New/improved feature
• 💥 Breaking change

Checklist

• I tested my change in a Wasp app to verify that it works as intended.

• 🧪 Tests and apps:

  • I added unit tests for my change.
  • (if you fixed a bug) I added a regression test for the bug I fixed.
  • (if you added/updated a feature) I added/updated e2e tests in examples/kitchen-sink/e2e-tests.
  • (if you added/updated a feature) I updated the starter templates in waspc/data/Cli/templates, as needed.
  • (if you added/updated a feature) I updated the example apps in examples/, as needed.
    • (if you updated examples/tutorials) I updated the tutorial in the docs (and vice versa).

• 📜 Documentation:

  • (if you added/updated a feature) I added/updated the documentation in web/docs/.

• 🆕 Changelog: (if change is more than just code/docs improvement)

  • I updated waspc/ChangeLog.md with a user-friendly description of the change.
  • (if you did a breaking change) I added a step to the current migration guide in web/docs/migration-guides/.
  • I bumped the version in waspc/waspc.cabal to reflect the changes I introduced.

[cprecioso]

• For ourselves, I'd make all the team use the lowest supported Node.js version in our development enviroments (Right now we say 22.12 in our documentation).
• I wouldn't like to have one more place where we have to remember to change the version numbers, especially if it's not grep-able in our codebase. I see you removed a comment about .nvmrc, maybe we can go back to some way of declaratively saying which node.js version we use and have everywhere use that?

[sodic]

For ourselves, I'd make all the team use the lowest supported Node.js version in our development enviroments

I agree

I wouldn't like to have one more place where we have to remember to change the version numbers, especially if it's not grep-able in our codebase... maybe we can go back to some way of declaratively saying which node.js version we use and have everywhere use that?

Fair enough, but where else would I put it to make it work with GH actions?

[cprecioso]

Fair enough, but where else would I put it to make it work with GH actions?

Something like this?

steps:
  - uses: actions/checkout@v6

  - id: get-node-version
    run: echo "node-version=$(cat .nvmrc)" >> $GITHUB_OUTPUT

  - uses: actions/setup-node@v6
    with:
      node-version: ${{ steps.get-node-version.outputs.node-version }}

[cprecioso]

In fact, reading from the docs, this is allowed

steps:
  - uses: actions/checkout@v6

  - uses: actions/setup-node@v6
    with:
      node-version-file: .nvmrc