Add ADR 0040 - Display front cover for books in Preview Panel (#12122)

* Create 0040-display-front-cover-in-preview-tab.md

* Remove numbers from headings in 0040-display-front-cover-in-preview-tab.md

* Fix bad reason in PreviewPanel option 0040-display-front-cover-in-preview-tab.md

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* Add images for ADR 0040-display-book-cover

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docs/decisions/0040-display-front-cover-in-preview-tab.md

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+---
+parent: Decision Records
+nav_order: 40
+---
+
+# Display front cover for book citations in the Preview tab
+
+## Context and Problem Statement
+
+* Users have requested that the front covers of book citations are displayed in JabRef.
+* This is discussed on the [JabRef forum](https://discourse.jabref.org/t/display-cover-images-for-books/3647) and raised as a [feature request](https://github.com/JabRef/jabref/issues/10120).
+* We need to decide where the book cover should be placed.
+
+## Decision Drivers
+
+* It should not be obtrusive or distracting since the main use of JabRef is for articles not books.
+* It should not obstruct the view of existing GUI components, specifically the MainTable or the information in the EntryEditor's tabs.
+
+## Considered Options
+
+Place the book cover in:
+
+1. The existing SidePane
+2. A new SidePane
+3. The Preview panel of the EntryEditor
+4. A SplitPane next to the MainTable
+
+## Decision Outcome
+
+Chosen option: "The PreviewPanel of the EntryEditor".
+
+## Pros and Cons of the Options
+
+### Existing SidePane
+
+![Image: Placement in SidePane](0040-placement-in-sidepane.png)
+
+* Good, because it would be unobtrusive
+* Bad, because it would crowd other panels in the SidePane
+* Bad, because changing the size of the SidePane would affect both the MainTable and the EntryEditor.
+
+### New right-sided SidePane
+
+![Image: Placement in the new right-sided SidePane](0040-placement-in-new-sidepane.png)
+
+* Good, if integrated together with entry preview because it would make it easier to view a citation's preview.
+* Bad, because an extra SidePane would make the interface overly complex.
+
+### The PreviewPanel of the EntryEditor
+
+![Image: Placement in the Preview Panel](0040-placement-in-preview-panel.png)
+
+* Good, because it would not be obtrusive or distracting.
+* Bad, if the Entry Editor is closed, users will have to open the Entry Editor and navigate to the "Preview" or "Required fields" tab to see the cover.
+
+### SplitPane next to the MainTable
+
+![Image: Placement next to the Main Table](0040-placement-in-maintable.png)
+
+* Good, because changing the size of this SplitPane would [only affect the MainTable](https://github.com/user-attachments/assets/4e458099-ca5c-41bc-a33b-ce4240d7df82).
+* Bad, because it would obstruct some columns in the MainTable.