feat: switch GitHub Actions to build optimized Docker image by default

- Change main build to use Dockerfile.optimized (targets ~200MB image)
- Add separate 'full' build job for development variant (2.6GB)
- Update tagging strategy: 'latest' for optimized, 'full' suffix for full variant
- Update documentation to reflect dual image strategy
- Update docker-compose.yml with variant selection comment

This provides users with two options:
- Optimized (default): Pre-built database, minimal size, for production
- Full: Complete n8n packages, dynamic scanning, for development

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

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

docs/RELEASE_GUIDE.md

@@ -15,11 +15,18 @@ git push origin v1.2.3
 ```
 
 This will automatically create the following Docker tags:
+
+**Optimized Images:**
 - `ghcr.io/czlonkowski/n8n-mcp:1.2.3` (exact version)
 - `ghcr.io/czlonkowski/n8n-mcp:1.2` (minor version)
 - `ghcr.io/czlonkowski/n8n-mcp:1` (major version)
 - `ghcr.io/czlonkowski/n8n-mcp:latest` (if from main branch)
 
+**Full Images:**
+- `ghcr.io/czlonkowski/n8n-mcp:1.2.3-full` (exact version)
+- `ghcr.io/czlonkowski/n8n-mcp:1.2-full` (minor version)
+- `ghcr.io/czlonkowski/n8n-mcp:full` (if from main branch)
+
 ## Tag Types Explained
 
 ### Latest Tag