chore: setup MinIO as local CDN for email development

Author: dandelionn

.devcontainer/.env.production.local.example

@@ -39,6 +39,7 @@ SUPPORT_EMAIL=support@app.com
 
 EMAIL_FRONTEND_BASE_URL=http://localhost:3000/frontend/
 EMAIL_BACKEND_BASE_URL=http://localhost:3000/backend/
-EMAIL_ASSETS_BASE_URL=http://localhost:3000/assets/
+# CDN Configuration (MinIO for email assets in development)
+CDN_URL=http://localhost:9000/public-assets
 
 PRINT_LOGS_TO_CONSOLE=true

.devcontainer/cdn-assets/README.md

@@ -0,0 +1,57 @@
+# CDN Assets
+
+This folder contains assets that are served directly by MinIO via volume mapping for use in email templates and other static content.
+
+**Note**: Files in this folder are directly accessible to the MinIO container via volume mapping - no upload process needed!
+
+## Files Included
+
+### Static Directory (`static/`)
+- `logo.png` - Company logo for email headers (150x45px recommended)
+- `header.png` - Header image for emails
+- `footer.png` - Footer image for emails
+- `logo.svg` - Vector version of the logo
+- `logo-placeholder.png` - Placeholder logo image
+- `icons/email-icon.png` - Email-related icons
+
+### Root Directory
+- `email-header.jpg` - Header image for email templates (600x200px recommended)
+- `company-icon.svg` - Scalable company icon
+- `email-footer.png` - Footer image for email branding (600x100px recommended)
+
+## How to Use
+
+### 1. Start MinIO
+```bash
+docker-compose -f .devcontainer/docker-compose.dev.yml up -d
+```
+
+### 2. Access via Public URLs
+Once MinIO is running, you can access these assets directly via:
+- `http://localhost:9000/public-assets/static/logo.png`
+- `http://localhost:9000/public-assets/static/header.png`
+- `http://localhost:9000/public-assets/static/footer.png`
+- `http://localhost:9000/public-assets/email-header.jpg`
+- `http://localhost:9000/public-assets/company-icon.svg`
+- `http://localhost:9000/public-assets/email-footer.png`
+
+### 3. Use in Email Templates
+In your email templates, use the environment variable:
+```javascript
+const logoUrl = `${process.env.CDN_URL}/static/logo.png`;
+// Results in: http://localhost:9000/public-assets/static/logo.png
+```
+
+## Replacing with Real Assets
+
+To use real image files:
+1. Replace the placeholder files with actual PNG/JPG/SVG files
+2. Keep the same filenames
+3. Restart MinIO: `docker-compose -f .devcontainer/docker-compose.dev.yml restart minio`
+
+## Production Setup
+
+For production, update the `CDN_URL` environment variable to point to your production CDN:
+```bash
+CDN_URL=https://your-cdn-domain.com/assets
+```