Duplicate, delete dialogs and save status in the form document (BITS-282 part d)

[PhilReinking]

Last part of the document editor: Duplicate, the delete dialogs and the save status work in the document, and the docs describe the new editor.

Fixes BITS-282

• Duplicate is in the question menu, not on groups (the server can't copy them). The copy opens below; a waiting change is saved first.
• An opened question gets the cursor at the end of its text.
• Delete… opens the dialog from Ask before deleting a question, naming its answers and the rules that use it #269, naming a question by number and text. Focus goes to the next row, else the one above, else Add question.
• useDeleteBlock().confirm resolves once the server answered, so focus moves after the delete.
• Save status sits in the top bar at a fixed width so the bar doesn't shift. Icons with a tooltip under 1280 px; under 1024 px Retry stays in the red bar.
• Docs: editor, outline (was Storyboard, same address), blocks and logic pages.

Tested: vitest, lint, vue-tsc, build, docs build; by hand at 1440, 1024, 390, 360; the review fixes at 1440, 1024, 390. Save-first and cursor tests fail without the fix.

Not tested: a form with real answers (faked counts in the browser). No CI: stacked PR.

🤖 Generated with Claude Code

[PhilReinking]

OK at 4c262ff. No CI (stacked), local runs: Vitest 364, lint, vue-tsc, build and the docs build pass. The save-first test fails without the fix. On a 4-worker server the copy kept text typed right before Duplicate, also in a group and after reload. Duplicate and delete work by keyboard and touch. After a delete the cursor goes to the next row or Add question; a failed delete keeps it on the row.

[PhilReinking]

OK at e859a30. No CI (stacked), local runs: Vitest 368, lint, vue-tsc and the build pass. 8 new or changed tests fail on 4c262ff. In the browser at 1440, 1024 and 390 the top bar stays put through saving, saved and idle. A question opens with the cursor at the end, and a click at the start of its text keeps that spot. A copy's delete dialog says "Question 2 (…)", and failed deletes and copies say what failed.

[PhilReinking]

Landed in main with #282 (the editor rebuild as one PR); this PR's commits are part of it.