When the user manually changes the project plan, we need to parse and recalculate the list of modules (more details in the [ADR|https://docs.google.com/document/d/1BH0SmaNPlnmAuyypv8zY98hT07GKGq-sUYxbQP9werI/edit?tab=t.0).

We need to

• trigger that action from the UI (a button)
• implement the POST /projects/[projectId]/modules
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