feat(workflow-form): Form View edit mode, with instruction and result authoring #8026

Task Summary

Add the edit mode of the Form View page and the page-level authoring it enables. (Split from the original authoring task: the inputs themselves are authored in #8027.)

• toggleAuthoring: with write access, Edit turns the page into in-place authoring; Done returns it to the reader state. Edit mode is the only state that enables workflow modification on this page, and entering it is refused without write access at the method itself.
• The inspect panel goes live in edit mode (acts as an editor, expose tick boxes on, inert off), so the author opens a step on the embedded preview and chooses which of its settings people fill in; the embedded preview's right-click menu carries the structure lock so the preview cannot be re-shaped.
• Write the author's instruction in place (heading in the header, markdown body with Write / Preview).
• Pick which extra results to feature: the non-terminal view-result steps; the final step's result always shows.
• Open canvas saves first and hands over only once the save has completed.

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other