fix block editor not changing content when switching to a new activity

[Weiko]

WIP

[greptile-apps]

PR Summary

This PR introduces a new hook useReplaceBlockEditorContent to manage block editor content synchronization, replacing the previous state management approach using activityBodyFamilyState.

• Unsafe JSON.parse in useReplaceBlockEditorContent.tsx lacks error handling, risking runtime exceptions
• Editor parameter typed as any in useReplaceBlockEditorContent reduces type safety
• Potential race condition in RichTextEditor.tsx between content updates and editor state synchronization
• replaceBlocks call in useReplaceBlockEditorContent appears to have incorrect parameter order
• Removal of debounced state updates could impact drag-and-drop performance

_{2 file(s) reviewed, 3 comment(s)
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[greptile-apps]

style: editor type should be properly typed rather than 'any' to ensure type safety

[greptile-apps]

logic: JSON.parse could throw if body contains invalid JSON. Wrap in try/catch and provide fallback

[greptile-apps]

logic: replaceBlockEditorContent() called directly in render function could cause infinite re-renders or race conditions. Should be in useEffect.