fix content image double-suffix, clean up page defaults and editor UX

- Fix resolve_content_image returning base path (not full URL) so
  responsive_image doesn't double-append width/extension
- Remove legacy image fields (image_src, image_alt, image_url) from
  block settings schemas
- Remove demo/mockup fallbacks from renderer and defaults — blank
  fields stay blank instead of showing preview content
- Replace demo text in defaults with instructional placeholders that
  guide new shop owners
- Remove redundant X button from editor sidebar, add unsaved-changes
  confirmation to Done button
- Fix block card name overflow on mobile (display: block, flex-wrap)
- Add onboarding UX improvement plan (10 tasks)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PROGRESS.md

@@ -51,6 +51,21 @@ All 4 phases done. Tailwind utility clone deleted, all templates migrated to sem
 | 70 | Margin guard on sales (prevent discounts that breach minimum profit threshold) | 69 | 1h | planned |
 | 71 | Announcement bar (dismissable shop banner for active sales) | 69 | 1.5h | planned |
 
+### Onboarding UX improvements ([plan](docs/plans/onboarding-ux.md))
+
+| # | Task | Priority | Est | Status |
+|---|------|----------|-----|--------|
+| 1 | Redirect to dashboard after wizard completion with welcome flash | High | 30m | planned |
+| 2 | Add shipping setup to checklist, gate "Go live" on shipping existing | High | 1h | planned |
+| 3 | Add shop settings to checklist (name, currency) | High | 45m | planned |
+| 4 | Make checklist collapsible instead of dismissable | Medium | 15m | planned |
+| 5 | Add test order guidance (test card number, what to expect) | Medium | 45m | planned |
+| 6 | Skip completed wizard steps on revisit | Medium | 1h | planned |
+| 7 | Better provider connection error messages with help links | Medium | 30m | planned |
+| 8 | Add theme customisation tips to checklist | Low | 15m | planned |
+| 9 | Smarter "Sync products" checklist link | Low | 15m | planned |
+| 10 | Add email setup as optional checklist item | Low | 30m | planned |
+
 ### Platform site
 
 | # | Task | Depends on | Est | Status |
@@ -93,4 +108,5 @@ All plans in [docs/plans/](docs/plans/). Completed plans are kept as architectur
 | [favicon.md](docs/plans/favicon.md) | Complete |
 | [legal-page-generator.md](docs/plans/legal-page-generator.md) | Complete |
 | [url-redirects.md](docs/plans/url-redirects.md) | Complete |
+| [onboarding-ux.md](docs/plans/onboarding-ux.md) | Planned |
 | [profit-aware-pricing.md](docs/plans/profit-aware-pricing.md) | Planned |