add Site context with social links editor and site-wide settings

- Add Site context for managing site-wide content (social links, nav items,
  announcement bar, footer content)
- Add SocialLink schema with URL normalization and platform auto-detection
  supporting 40+ platforms via host and 25+ via URI scheme
- Add NavItem schema for header/footer navigation (editor UI coming next)
- Add SiteEditor component with collapsible sections for each content type
- Wire social links card block and footer to use database data
- Filter empty URLs from display in shop components
- Add DetailsPreserver hook to preserve collapsible section state
- Add comprehensive tests for Site context and SocialLink functions
- Remove unused helper functions from onboarding to fix compiler warnings
- Move sync_edit_url_param helper to group handle_editor_event clauses

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

PROGRESS.md

@@ -149,21 +149,33 @@ Close critical gaps identified in the competitive analysis. Phased approach: cor
 | 100 | Blog post type | — | 3h | planned |
 | 101 | Staff accounts & RBAC | — | 4h | planned |
 
-### Editor panel reorganisation ([plan](docs/plans/editor-reorganisation.md))
+### Editor panel reorganisation ([plan](docs/plans/editor-reorganisation.md)) — In Progress
 
 Restructure the 3-tab editor panel for better discoverability. Replace Settings tab with Site tab for site-wide content (announcement bar text, social links, nav items, footer content). Move branding from Theme to Site. Merge page settings inline into Page tab.
 
 | # | Task | Est | Status |
 |---|------|-----|--------|
-| 1-4 | Data model + Site tab skeleton | 3h | planned |
-| 5-7 | Announcement bar (editable text, link, styles) | 1.5h | planned |
-| 8-9 | Social links editor | 2h | planned |
+| 1-4 | Data model + Site tab skeleton | 3h | done |
+| 5-7 | Announcement bar (editable text, link, styles) | 1.5h | done |
+| 8-9 | Social links editor | 2h | done |
 | 10-14 | Header & footer navigation editors | 3h | planned |
-| 15-16 | Footer content (about, copyright, newsletter toggle) | 1.25h | planned |
+| 15-16 | Footer content (about, copyright, newsletter toggle) | 1.25h | done |
 | 17-18 | Move branding from Theme to Site | 1.5h | planned |
 | 19-20 | Merge page settings into Page tab, remove Settings tab | 1h | planned |
 | 21-22 | Polish and testing | 2h | planned |
 
+### Unified editor session ([plan](docs/plans/unified-editor-session.md)) — Complete
+
+Unified "optimistic preview with explicit save" across all editor tabs. Changes show immediately but only persist on Save. Free tab switching without warnings. Navigation blocking with Save/Discard/Cancel modal.
+
+| Phase | Description | Est | Status |
+|-------|-------------|-----|--------|
+| 1 | Site tab preview without auto-save | 1h | done |
+| 2 | Theme tab preview without auto-save | 1.5h | done |
+| 3 | Unified Save button (saves all dirty tabs) | 1h | done |
+| 4 | Visual indicators (dirty dots on tabs, "Unsaved" text) | 0.5h | done |
+| 5 | Navigation warning modal (Save & continue, Discard, Cancel) | 1h | done |
+
 ### SEO enhancements ([plan](docs/plans/seo-enhancements.md))
 
 Comprehensive SEO tooling to rival Yoast/RankMath. Per-page SEO controls, enhanced schema, SEO preview panel, focus keyword with scoring, FAQ schema, Search Console integration.