Add edit modals and image upload for admin dashboard

User Interface Improvements:
- Added edit modal for skills with activate/deactivate checkbox
- Added edit modal for social links with activate/deactivate checkbox
- Skills and social links now default to "active" when created
- Better UX with inline editing instead of separate pages

Image Upload Feature:
- Implemented file upload for project images
- Support for png, jpg, jpeg, gif, webp (max 16 MB)
- Automatic filename sanitization and timestamp prefixing
- Preview of current image in edit mode
- Option to upload file OR enter manual URL
- Files saved to static/img/ directory

Modified Files:
- app.py: Added upload configuration (MAX_CONTENT_LENGTH, UPLOAD_FOLDER, ALLOWED_EXTENSIONS)
- routes/admin.py: Added save_uploaded_file() helper and file handling in project routes
- templates/admin/skills.html: Added edit modal with is_active checkbox
- templates/admin/social_links.html: Added edit modal with is_active checkbox
- templates/admin/project_form.html: Added file upload input with preview

Benefits:
- No more "inactive" items when creating new entries
- Easy toggle of active/inactive state
- Professional image upload with validation
- Better user experience overall

app.py

@@ -24,6 +24,11 @@ app.config['SQLALCHEMY_DATABASE_URI'] = config.SQLALCHEMY_DATABASE_URI
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = config.SQLALCHEMY_TRACK_MODIFICATIONS
 app.config['SQLALCHEMY_ECHO'] = config.SQLALCHEMY_ECHO
 
+# File upload configuration
+app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # 16 MB max file size
+app.config['UPLOAD_FOLDER'] = 'static/img'
+app.config['ALLOWED_EXTENSIONS'] = {'png', 'jpg', 'jpeg', 'gif', 'webp'}
+
 # Initialize extensions
 db.init_app(app)
 bcrypt.init_app(app)