Add comprehensive database integration, authentication, and admin dashboard

This commit introduces major enhancements to Talk2Me:

## Database Integration
- PostgreSQL support with SQLAlchemy ORM
- Redis integration for caching and real-time analytics
- Automated database initialization scripts
- Migration support infrastructure

## User Authentication System
- JWT-based API authentication
- Session-based web authentication
- API key authentication for programmatic access
- User roles and permissions (admin/user)
- Login history and session tracking
- Rate limiting per user with customizable limits

## Admin Dashboard
- Real-time analytics and monitoring
- User management interface (create, edit, delete users)
- System health monitoring
- Request/error tracking
- Language pair usage statistics
- Performance metrics visualization

## Key Features
- Dual authentication support (token + user accounts)
- Graceful fallback for missing services
- Non-blocking analytics middleware
- Comprehensive error handling
- Session management with security features

## Bug Fixes
- Fixed rate limiting bypass for admin routes
- Added missing email validation method
- Improved error handling for missing database tables
- Fixed session-based authentication for API endpoints

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

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

admin/templates/dashboard_simple.html

@@ -0,0 +1,120 @@
+{% extends "base.html" %}
+
+{% block title %}Dashboard - Talk2Me Admin{% endblock %}
+
+{% block content %}
+<!-- Simple Mode Notice -->
+<div class="alert alert-warning" role="alert">
+    <h4 class="alert-heading">Simple Mode Active</h4>
+    <p>The admin dashboard is running in simple mode because Redis and PostgreSQL services are not available.</p>
+    <hr>
+    <p class="mb-0">To enable full analytics and monitoring features, please ensure Redis and PostgreSQL are running.</p>
+</div>
+
+<!-- Basic Info Cards -->
+<div class="row mb-4">
+    <div class="col-md-4 mb-3">
+        <div class="card">
+            <div class="card-body">
+                <h5 class="card-title">System Status</h5>
+                <p class="card-text">
+                    <span class="badge badge-success">Online</span>
+                </p>
+                <small class="text-muted">Talk2Me API is running</small>
+            </div>
+        </div>
+    </div>
+    
+    <div class="col-md-4 mb-3">
+        <div class="card">
+            <div class="card-body">
+                <h5 class="card-title">Admin Access</h5>
+                <p class="card-text">
+                    <span class="badge badge-primary">Authenticated</span>
+                </p>
+                <small class="text-muted">You are logged in as admin</small>
+            </div>
+        </div>
+    </div>
+    
+    <div class="col-md-4 mb-3">
+        <div class="card">
+            <div class="card-body">
+                <h5 class="card-title">Services</h5>
+                <p class="card-text">
+                    Redis: <span class="badge badge-secondary">Not configured</span><br>
+                    PostgreSQL: <span class="badge badge-secondary">Not configured</span>
+                </p>
+            </div>
+        </div>
+    </div>
+</div>
+
+<!-- Available Actions -->
+<div class="card">
+    <div class="card-header">
+        <h5 class="mb-0">Available Actions</h5>
+    </div>
+    <div class="card-body">
+        <p>In simple mode, you can:</p>
+        <ul>
+            <li>Access the Talk2Me API with admin privileges</li>
+            <li>View system health status</li>
+            <li>Logout from the admin session</li>
+        </ul>
+        
+        <p class="mt-3">To enable full features, set up the following services:</p>
+        <ol>
+            <li><strong>Redis</strong>: For caching, rate limiting, and session management</li>
+            <li><strong>PostgreSQL</strong>: For persistent storage of analytics and user data</li>
+        </ol>
+        
+        <div class="mt-4">
+            <a href="/admin/logout" class="btn btn-secondary">Logout</a>
+        </div>
+    </div>
+</div>
+
+<!-- Setup Instructions -->
+<div class="card mt-4">
+    <div class="card-header">
+        <h5 class="mb-0">Quick Setup Guide</h5>
+    </div>
+    <div class="card-body">
+        <h6>1. Install Redis:</h6>
+        <pre class="bg-light p-2"><code># Ubuntu/Debian
+sudo apt-get install redis-server
+sudo systemctl start redis
+
+# macOS
+brew install redis
+brew services start redis</code></pre>
+        
+        <h6>2. Install PostgreSQL:</h6>
+        <pre class="bg-light p-2"><code># Ubuntu/Debian
+sudo apt-get install postgresql
+sudo systemctl start postgresql
+
+# macOS
+brew install postgresql
+brew services start postgresql</code></pre>
+        
+        <h6>3. Configure Environment:</h6>
+        <pre class="bg-light p-2"><code># Add to .env file
+REDIS_URL=redis://localhost:6379/0
+DATABASE_URL=postgresql://user:pass@localhost/talk2me</code></pre>
+        
+        <h6>4. Initialize Database:</h6>
+        <pre class="bg-light p-2"><code>python init_auth_db.py</code></pre>
+        
+        <p class="mt-3">After completing these steps, restart the Talk2Me server to enable full admin features.</p>
+    </div>
+</div>
+{% endblock %}
+
+{% block scripts %}
+<script>
+// Simple mode - no need for real-time updates or API calls
+console.log('Admin dashboard loaded in simple mode');
+</script>
+{% endblock %}