Bug: Drag-and-drop does not open files in editor

[petertzy]

Description
When dragging and dropping a file into the editor, the file is not opened. The editor does not respond to the drop action.

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Steps to Reproduce

1. Open the application
2. Drag a file (e.g. .md, .txt, .pdf, etc.) into the editor area
3. Drop the file

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Expected Behavior
The file should be opened in a new editor tab (or processed accordingly if conversion is needed).

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Actual Behavior
Nothing happens after dropping the file. The file is not opened.

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Environment

• OS: (e.g. macOS / Windows / Linux)
• App version: (if applicable)

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Additional Notes

• This may be related to missing drag-and-drop event handling in the editor component
• Should align with existing file open logic (e.g. handleOpenFile)