Enhancement: Dedicated edit button for rendered code-blocks

Follow up from #10137

Description


Problem: Confusing Code Block Interaction

The current method for editing rendered code blocks (e.g., diagrams) is a "click-to-edit" action on the preview. This interaction creates a poor user experience because a single click has multiple possible outcomes, such as:
• Opening the code editor (for editing).
• Displaying the block's toolbar (for options).
• Entering lightbox/full-screen mode (for diagrams).

This ambiguity can lead to frustration when users accidentally open the editor instead of viewing the toolbar or lightbox.

Solution: Dedicated Edit Button

To resolve this conflict and streamline the editing workflow, we can add an explicit "Edit" button to the block's toolbar. This clear, dedicated button will open the code editor, ensuring that editing is always an intentional action.