- Extract content from formData.content instead of passing whole object
- Add logic to call updateContent() for existing content vs createContent() for new
- Fix 400 Invalid JSON error caused by sending object instead of string
- Handle different formData formats: string, {content: string}, {text: string}
The frontend was sending html_content as {type:'html', content:'...'} object
but server expected a plain string. Now properly extracts the content value.