This removes the deprecated AITaskPromptParameterName constant and all
backward compatibility code that was added for v2.28.
- Remove AITaskPromptParameterName constant from codersdk/aitasks.go
- Remove backward compatibility code in coderd/aitasks.go that populated
the "AI Prompt" parameter for templates that defined it
- Remove the backward compatibility test (OK AIPromptBackCompat)
- Update dbfake to no longer set the AI Prompt parameter
- Remove AITaskPromptParameterName from frontend TypeScript types
- Remove preset prompt read-only feature from TaskPrompt component
- Update docs to reflect that pre-2.28 definition is no longer supported
Task prompts are now exclusively stored in the tasks.prompt database
column, as introduced in the migration that added the tasks table.