feat: Add SilverSHELL SDK documentation page with downloadable templates

Added comprehensive SDK page at /sdk with:
- Downloadable SilverSHELL starter template (6.3 KB)
- Downloadable SilverSHELL module template (14 KB)
- Quick start guide with step-by-step instructions
- Creating applications guide (configuration, UI, manual install)
- Creating modules guide with template options
- Publishing modules guide (automated CI/CD + manual)
- Available modules list from library.silverlabs.uk
- Resources and support links

Initial commit includes:
- Complete static website with Docker deployment
- SilverLabs branding and styling
- Nginx configuration for production serving

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

docker-compose.yml

@@ -0,0 +1,18 @@
+version: '3.8'
+
+services:
+  silverlabs-web:
+    build: .
+    container_name: silverlabs-web
+    restart: unless-stopped
+    ports:
+      - "8210:80"
+    networks:
+      - web
+    labels:
+      - "com.silverlabs.service=website"
+      - "com.silverlabs.description=SilverLabs Landing Page"
+
+networks:
+  web:
+    external: false