feat: Completed Milestone 4 - Launchpad Site Builder

- Implemented Full Site Builder Suite:
- Sites Manager (Multi-site deployment management)
- Site Dashboard (Tabs for Pages, Nav, Theme)
- Page Editor (Visual Block Editor for Hero, Content, Features)
- Navigation Manager (Menu editor)
- Theme Settings (Global styles)
- Backend Schema (sites, pages, navigation, globals) setup script
- Integrated all components into /admin/sites pages

IMPLEMENTATION_ROADMAP.md

@@ -458,20 +458,34 @@ frontend/src/components/admin/content/PagesManager.tsx
 frontend/src/components/admin/content/ArticlesManager.tsx
 ```
 
-**Command**:
-```bash
-cd /Users/christopheramaya/Downloads/spark/frontend/src
-mkdir -p pages/admin/sites
-mkdir -p components/admin/sites
-mkdir -p components/admin/content
-touch pages/admin/sites/index.astro
-touch pages/admin/content/posts.astro
-touch pages/admin/content/pages.astro
-touch components/admin/sites/SitesManager.tsx
-touch components/admin/content/PostsManager.tsx
-touch components/admin/content/PagesManager.tsx
-touch components/admin/content/ArticlesManager.tsx
-```
+---
+
+## 🎯 MILESTONE 4: LAUNCHPAD - SITE BUILDER
+
+**Goal**: Build a fully functional site builder for managing sites, pages, navigation, and global settings.
+
+#### Task 4.1: Sites Manager & Dashboard ✅ (COMPLETED)
+**What Was Built**:
+- ✅ Sites Collection & Manager
+- ✅ Site Dashboard with Tabs (Pages, Nav, Theme)
+- ✅ Launchpad Schema Setup
+
+#### Task 4.2: Page Builder ✅ (COMPLETED)
+**What Was Built**:
+- ✅ Block-based Page Editor (Hero, Content, Features)
+- ✅ Real-time JSON state management
+- ✅ Draft/Published status workflow
+- ✅ /admin/sites/editor/[id]
+
+#### Task 4.3: Navigation & Globals ✅ (COMPLETED)
+**What Was Built**:
+- ✅ Navigation Editor (Add/Sort links)
+- ✅ Theme Settings (Colors, Logo, Footer)
+- ✅ Global singleton schema
+
+#### Task 4.4: Launchpad Frontend
+**What to Build**:
+- Integrate Next.js frontend to fetch this data (Future Phase)
 
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