fix(form): keep the Start-in choice in the autosaved draft #99

Follow-up to #88.

Problem #

FormDraft.dryRun is saved only in the stash written before a scope-upgrade redirect. The regular autosave doesn't include it. So a user who picks Live, leaves the page, and comes back to the restored draft finds Dry run selected again, and may create the automation in the wrong mode without noticing.

Evidence #

• app/islands/AutomationForm.tsx:540: FormDraft.dryRun, filled in the scope-upgrade stash only.
• app/islands/AutomationForm.tsx:688: the restore falls back to true when the draft has no dryRun.

Expected #

Every saved draft keeps the Start-in choice, and restoring it brings back what the user picked.

Acceptance criteria #

• The autosave includes dryRun.
• A test picks Live, triggers an autosave, remounts the form from the draft, and finds Live selected.