feat: Complete Mail Composer with EmailJS integration

- Rich email composer with formatting tools (bold, italic, underline, links)
- Multi-recipient support (To, CC, BCC fields)
- File attachments with drag & drop support
- Priority levels and email validation
- Draft management with auto-save and cloud sync
- Real email sending via EmailJS integration
- Responsive design for mobile and desktop
- Comprehensive error handling and fallback modes
- Complete documentation and setup guides
- Firebase integration ready for advanced features

Features:
✅ Real email sending (EmailJS)
✅ Rich text editor
✅ File attachments
✅ Draft management
✅ Form validation
✅ Responsive UI
✅ Error handling
✅ Documentation

EMAILJS_TEMPLATE_FIX.md

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+# 🔧 Fix EmailJS Template - "Recipients address is empty" Error
+
+## Problem
+EmailJS is expecting specific variable names in your template that match what the app is sending.
+
+## Solution: Update Your EmailJS Template
+
+### 1. Go to EmailJS Dashboard
+1. Visit [EmailJS Dashboard](https://dashboard.emailjs.com/)
+2. Go to **Email Templates**
+3. Click on your template (`template_nlh9jpe`)
+
+### 2. Update Template Settings
+
+**To Email Field:**
+```
+{{to_email}}
+```
+
+**Subject Field:**
+```
+{{subject}}
+```
+
+**Content/Body Field:**
+```html
+<h3>New Email from Mail Composer</h3>
+
+<p><strong>From:</strong> {{from_name}}</p>
+<p><strong>To:</strong> {{to_email}}</p>
+<p><strong>CC:</strong> {{cc_email}}</p>
+<p><strong>BCC:</strong> {{bcc_email}}</p>
+<p><strong>Priority:</strong> {{priority}}</p>
+
+<hr>
+
+<div>
+{{{message}}}
+</div>
+
+<hr>
+<p><em>Sent via Mail Composer App</em></p>
+<p><em>Reply to: {{reply_to}}</em></p>
+```
+
+### 3. Important Settings
+
+Make sure these settings are correct in your template:
+
+- **To Email**: `{{to_email}}`
+- **From Name**: Your name or "Mail Composer"
+- **From Email**: Your verified email address
+- **Subject**: `{{subject}}`
+
+### 4. Save Template
+
+Click **Save** after making these changes.
+
+## 🧪 Test Again
+
+After updating the template:
+
+1. **Refresh your mail composer app**
+2. **Try sending a test email** to yourself
+3. **Check for success message**: "Email sent successfully via EmailJS!"
+
+## 🔍 Debug Tips
+
+If it still doesn't work:
+
+1. **Check browser console** (F12) for detailed error messages
+2. **Verify email addresses** are valid
+3. **Try sending to yourself first**
+4. **Check EmailJS dashboard** for send logs
+
+## ✅ Expected Result
+
+After fixing the template, you should see:
+- ✅ Success message in the app
+- 📧 Email in recipient's inbox
+- 📊 Successful send in EmailJS dashboard
+
+Try updating your template and test again!