Plans that fail to load give no hints to what went wrong

"Retry or go back" doesn't give us much to go on. Could be an API issue (not callable, db constraint, etc) could be problem with React not liking the data coming from API, who knows.

We should pass on a more descriptive error to the user (and include something friendly like who to reach out to) if there is a problem. This will speed up troubleshooting issues that will come up.

The issue names no file or test. Start by reproducing a failed plan load and tracing the React/TypeScript error path around the existing “Retry or go back” message, then inspect the API response involved. Done means users receive a descriptive, friendly troubleshooting message that helps identify where to seek support.

Written by the indexing model from the issue text.