Add authentication system and admin dashboard

Security Features:
- Added User model with bcrypt password hashing
- Implemented Flask-Login for session management
- Protected all API write operations with @login_required decorator
- Added authentication routes (login/logout)

Admin Dashboard:
- Created comprehensive admin dashboard with statistics
- Profile management interface
- Skills management (add/edit/delete)
- Projects management with full CRUD operations
- Social links management
- Modern responsive UI with Bootstrap 5

New Files:
- models.py: Added User model with bcrypt
- routes/auth.py: Login/logout functionality
- routes/admin.py: Complete admin dashboard with CRUD operations
- templates/auth/login.html: Login page
- templates/admin/base.html: Admin base template
- templates/admin/dashboard.html: Main dashboard
- templates/admin/profile.html: Profile editor
- templates/admin/skills.html: Skills manager
- templates/admin/projects.html: Projects list
- templates/admin/project_form.html: Project editor
- templates/admin/social_links.html: Social links manager

Modified Files:
- app.py: Integrated Flask-Login and bcrypt, registered new blueprints
- requirements.txt: Added Flask-Login, Flask-Bcrypt, bcrypt
- init_db.py: Creates default admin user (admin/admin123)
- routes/api.py: Protected all write operations with authentication

Default Credentials:
- Username: admin
- Password: admin123
- ⚠️ MUST be changed after first login!

Benefits:
- Secure API access with session-based authentication
- User-friendly admin interface for content management
- No need to edit code or database directly
- Bcrypt password hashing for security
- Protected against unauthorized access

templates/admin/projects.html

@@ -0,0 +1,52 @@
+{% extends "admin/base.html" %}
+
+{% block title %}Gestione Progetti{% endblock %}
+{% block page_title %}Gestione Progetti{% endblock %}
+
+{% block content %}
+<div class="mb-3">
+    <a href="{{ url_for('admin.project_add') }}" class="btn btn-gradient">
+        <i class="fas fa-plus me-2"></i>Nuovo Progetto
+    </a>
+</div>
+
+<div class="row g-4">
+    {% for project in projects %}
+    <div class="col-md-4">
+        <div class="card h-100">
+            {% if project.image_url %}
+            <img src="{{ url_for('static', filename=project.image_url) }}" class="card-img-top" alt="{{ project.title }}">
+            {% endif %}
+            <div class="card-body">
+                <h5 class="card-title">{{ project.title }}</h5>
+                <p class="card-text text-muted small">{{ project.description[:100] }}...</p>
+                <div class="mb-2">
+                    {% for tag in project.tags %}
+                    <span class="badge {{ tag.color_class }} me-1">{{ tag.name }}</span>
+                    {% endfor %}
+                </div>
+                <div class="d-flex justify-content-between align-items-center">
+                    <small class="text-muted">
+                        {% if project.is_published %}
+                            <i class="fas fa-eye text-success"></i> Pubblicato
+                        {% else %}
+                            <i class="fas fa-eye-slash text-danger"></i> Bozza
+                        {% endif %}
+                    </small>
+                    <div>
+                        <a href="{{ url_for('admin.project_edit', project_id=project.id) }}" class="btn btn-sm btn-outline-primary">
+                            <i class="fas fa-edit"></i>
+                        </a>
+                        <form method="POST" action="{{ url_for('admin.project_delete', project_id=project.id) }}" class="d-inline">
+                            <button type="submit" class="btn btn-sm btn-outline-danger" onclick="return confirm('Sicuro di voler eliminare?')">
+                                <i class="fas fa-trash"></i>
+                            </button>
+                        </form>
+                    </div>
+                </div>
+            </div>
+        </div>
+    </div>
+    {% endfor %}
+</div>
+{% endblock %}