Rebuild the form editor as one document

[PhilReinking]

Brings the reviewed editor stack into main in one PR: the form as one document, with its outline, type picker, rules in place, live preview and end screen.

Fixes BITS-279, BITS-282, BITS-283, BITS-284, BITS-285, BITS-286, BITS-287, BITS-295

The help text contrast in answer settings (2.4:1) comes from the UI kit and moves to BITS-289.

• Each included PR was reviewed OK at its head (list below). Ask before deleting a question, naming its answers and the rules that use it #269 and Preview mode in the public form app #270 landed in main first; this PR then merged main again.
• Main merge (cdb443c): conflicts only in CHANGELOG.md and Edit.vue's imports. Every changelog line kept once, main's wording for Duplicate a question through the API #262 and Preview mode for the public form: try a form without storing answers #266, plus Plain words in rule errors and the submit API docs #278.
• Second main merge (48d1d0b, after Ask before deleting a question, naming its answers and the rules that use it #269 and Preview mode in the public form app #270): conflict only in CHANGELOG.md. Ask before deleting a question, naming its answers and the rules that use it #269's line kept once, where main has it. No code changed against cdb443c.
• Edit.vue: main's loading skeletons were for the old page. The document has its own load state with Try again, so the stack's imports stay.
• No PHP, no migrations.

Heads-up: form owners get a new editor: the whole form in one column instead of the question list and workbench.

Tested: Vitest 504, lint, vue-tsc, build on both merges. By hand at 1440 and 390: load, open/close, add via picker, rule, preview, end screen, duplicate, delete, End screen tab.

Not tested: 1024, touch, screen reader, Safari, Firefox.

Known gap, older than the stack: a new Long text question has no options yet, so the preview logs one options.rows error.

Included PRs and fix commits

• Edit the whole form as one document (part 1) #268 BITS-282 part 1: the form as one document
• Form document: outline, tablet and phone layout #272 BITS-282 part b: outline, tablet and phone layout
• Move questions by keyboard, menu and drag (BITS-282 part c) #275 BITS-282 part c: move questions by keyboard, menu and drag
• Duplicate, delete dialogs and save status in the form document (BITS-282 part d) #277 BITS-282 part d: duplicate, delete dialogs, save status
• Add questions anywhere with a grouped type picker #276 BITS-283: add questions anywhere with a grouped type picker
• Show and edit logic rules where they act #274 BITS-284: rules where they act
• feat: show a live preview beside the document #273 BITS-285: live preview beside the document
• fix: show the end screen in the editor's preview #280 BITS-285: end screen in the preview, preview focus and Esc
• Show the end screen as the last block of the document #271 BITS-286: end screen as the last block
• Use the review's words across the editor #279 BITS-287: the review's words across the editor
• Mark where each question starts and give the open question room #281 BITS-295: question lines and room for the open question
• Ask before deleting a question, naming its answers and the rules that use it #269 BITS-279: delete dialogs (merged into main first)
• Preview mode in the public form app #270 BITS-285: public form preview mode (merged into main first)
• Stack fixes: 66ffab3 (end screen test after Add questions anywhere with a grouped type picker #276 and Show the end screen as the last block of the document #271), 637094a (preview reloads after a saved rule), 32f854b (empty form keeps Preview on a phone)

All reviewed OK at their heads; #281's last head only adds the merge of #280's reviewed head.

🤖 Generated with Claude Code

[PhilReinking]

OK at cdb443c, CI green (Vitest 504, PHP 746). The head is #281's ceadf5e plus one merge of main, and #281's last merge of #280 changes only CHANGELOG.md. The main merge takes main's newer version of 7 backend files from #262 and #278, where the stack has nothing of its own, and the stack's version of the other 154 files. Edit.vue keeps the stack's imports: the document's load state replaces main's skeletons. Every changelog line appears once.

[PhilReinking]

OK at 48d1d0b, CI green. The head merges main 6412370 into the reviewed cdb443c. Main's own commits were all in cdb443c already, so only CHANGELOG.md needed a hand fix: the PR's lines stay, and main's #278 and #269 lines keep main's words and order. Every changelog line appears once. Every other file equals cdb443c, and the diff against main touches only resources/, docs/, .vitepress and CHANGELOG.md.