[WIP] Replace SpicyPizza with direct .env file

[Claude]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

---

This section details on the original issue you should resolve

<issue_title>Replace SpicyPizza with direct .env file</issue_title>
<issue_description>SpicyPizza/create-envfile is a small GitHub Action that writes a .env file using values passed in the with: block.

We need to skip the action and write the .env file directly with a shell step.

No third-party action, so one less external dependency to trust with our secrets.
No fixed input schema, so no lint warnings.

</issue_description>

• Closes Footlight App:Replace SpicyPizza #2279

<agent_instructions>SpicyPizza/create-envfile is a small GitHub Action that writes a .env file using values passed in the with: block.
It scans all with: inputs prefixed with envkey_ at runtime and writes them into the .env file. These keys aren't fixed - they're whatever we pass in, so the action can't list them in advance.

linter checks with: keys against that fixed list, so any envkey_* key looks "invalid" to it. It's a false positive and the workflow still runs fine and the .env file is created correctly.

Best alternative

Skip the action and write the .env file directly with a shell step

No third-party action, so one less external dependency to trust with our secrets.
No fixed input schema, so no lint warnings.</agent_instructions>

Comments on the Issue (you are @claude[agent] in this section)

• Fixes Footlight App:Replace SpicyPizza #2279

[aws-amplify-ca-central-1]

This pull request is automatically being deployed by Amplify Hosting (learn more).

Access this pull request here: https://pr-2280.dla06mbe0wyl7.amplifyapp.com