### What needs to get done #### Context When using JSON schema IDE integration, it shows an error when using the 12 factor rock extensions. ```console Property extensions is not allowed. (yaml-schema: rockcraft 513) ``` #### Example The following is a minimal `rockcraft.yaml` example that shows the missing schema property: ```yaml name: my-rock-name base: ubuntu@24.04 version: "0.1" summary: A summary of your Flask application description: | This is my-rock-name's description. platforms: amd64: extensions: - flask-framework parts: flask-framework/install-app: prime: - flask/app/.env ``` ### Why it needs to get done Helps to make the Rockcraft JSON schema more complete.