feat: Complete markdown syntax refinement and variable protection

✅ New cleaner syntax implemented:
- [card:type] instead of [card type='type']
- [button:style](url)Text[/button] instead of [button url='...' style='...']
- Standard markdown images: ![alt](url)

✅ Variable protection from markdown parsing:
- Variables with underscores (e.g., {order_items_table}) now protected
- HTML comment placeholders prevent italic/bold parsing
- All variables render correctly in preview

✅ Button rendering fixes:
- Buttons work in Visual mode inside cards
- Buttons work in Preview mode
- Button clicks prevented in visual editor
- Proper styling for solid and outline buttons

✅ Backward compatibility:
- Old syntax still supported
- No breaking changes

✅ Bug fixes:
- Fixed order_item_table → order_items_table naming
- Fixed button regex to match across newlines
- Added button/image parsing to parseMarkdownBasics
- Prevented button clicks on .button and .button-outline classes

📚 Documentation:
- NEW_MARKDOWN_SYNTAX.md - Complete user guide
- MARKDOWN_SYNTAX_AND_VARIABLES.md - Technical analysis

TEMPLATE_SOURCE_OF_TRUTH.md

@@ -0,0 +1,128 @@
+# Template Source of Truth
+
+## Single Source of Truth: `/includes/Email/DefaultTemplates.php`
+
+This file contains **clean markdown templates** without HTML tags inside shortcodes.
+
+### Structure
+
+```php
+namespace WooNooW\Email;
+
+class DefaultTemplates {
+    public static function get_all_templates() {
+        return [
+            'customer' => [
+                'order_placed' => '...',
+                'order_confirmed' => '...',
+                'order_shipped' => '...',
+                'order_completed' => '...',
+                'order_cancelled' => '...',
+                'payment_received' => '...',
+                'payment_failed' => '...',
+                'registered' => '...',
+                'vip_upgraded' => '...',
+            ],
+            'staff' => [
+                'order_placed' => '...',
+                'order_confirmed' => '...',
+                'order_shipped' => '...',
+                'order_completed' => '...',
+                'order_cancelled' => '...',
+                'payment_received' => '...',
+                'payment_failed' => '...',
+            ],
+        ];
+    }
+    
+    public static function get_default_subject($recipient, $event) {
+        // Returns subject string
+    }
+}
+```
+
+### Template Format
+
+Templates use **clean markdown** inside `[card]` shortcodes:
+
+```markdown
+[card type="hero"]
+
+## Thank you for your order, {customer_name}!
+
+We've received your order and will begin processing it right away.
+[/card]
+
+[card]
+
+**Order Number:** #{order_number}
+**Order Date:** {order_date}
+**Order Total:** {order_total}
+
+[/card]
+
+[button url="{order_url}"]View Order Details[/button]
+```
+
+**NOT** HTML like this:
+```html
+[card type="hero"]
+<h1>Thank you for your order, {customer_name}!</h1>
+<p>We've received your order...</p>
+[/card]
+```
+
+## How It's Used
+
+### TemplateProvider.php
+
+`/includes/Core/Notifications/TemplateProvider.php` uses the Email templates:
+
+```php
+use WooNooW\Email\DefaultTemplates as EmailDefaultTemplates;
+
+// Get all templates
+$allEmailTemplates = EmailDefaultTemplates::get_all_templates();
+
+// Get specific template
+$body = $allEmailTemplates[$recipient_type][$template_name];
+$subject = EmailDefaultTemplates::get_default_subject($recipient_type, $template_name);
+```
+
+### Event ID Mapping
+
+API event IDs are mapped to template names:
+
+| API Event ID | Template Name |
+|-------------|---------------|
+| `order_processing` | `order_confirmed` |
+| `new_customer` | `registered` |
+| Others | Same name |
+
+## Deprecated Files
+
+### `/includes/Core/Notifications/DefaultEmailTemplates.php` ❌
+
+**DO NOT USE** - This file contains old templates with HTML tags inside shortcodes.
+
+It's kept for backwards compatibility only and is marked as deprecated.
+
+## Frontend Conversion
+
+When templates are loaded in the editor:
+
+1. **Database** stores HTML (for backwards compatibility)
+2. **converter.ts** converts HTML to clean markdown using `convertHtmlToMarkdown()`
+3. **CodeEditor** displays clean markdown
+4. **User edits** in markdown
+5. **Saves** back as HTML (via blocks → HTML conversion)
+
+This ensures smooth editing experience while maintaining compatibility.
+
+## Benefits
+
+✅ **Clean markdown editing** - No HTML tags in markdown mode
+✅ **Single source of truth** - One place to update templates
+✅ **Better UX** - Markdown toolbar and syntax highlighting
+✅ **Mobile-friendly** - Easy to type on any device
+✅ **Maintainable** - Clear separation of concerns