Move CKEditor to BlockNote Editor

Acceptance Criteria

• CKEditor is fully replaced with BlockNote across all relevant components.
• The new BlockNote editor includes image upload capabilities using the existing image-uploader.tsx.
• BlockNote editor functionalities are tested and verified to work as expected.

Sprint Ready Checklist

1. Acceptance criteria defined
2. Team understands acceptance criteria
3. Team has defined solution / steps to satisfy acceptance criteria
4. Acceptance criteria is verifiable / testable
5. External / 3rd Party dependencies identified