Do we really need 2048 x 2048? That's more than HD.
Minecraft Panorama
This Minecraft mod provides the ability to take panoramic screenshots at any time with the Screenshot key (default to F2 on most Minecraft installations). On top of that, these screenshots will occupy the main menu background, allowing you to relive your adventures every time you boot up the game.
Installing
There are two variants of this mod: One for Forge, and the other for Fabric. Each release comes with jar files for both. You can download the appropriate jar file and place it within the "mods" folder within your Minecraft installation. For more details, see the README files of the appropriate branches.
Building
Simply run the "gradle build" (or "./gradlew build" on OSX and Linux) to create a distributable jar file. You can find it within the build/libs directory.
Licensing
This mod is licensed under the GNU General Public License version 3.0. In short, you are allowed to use and modify this mod for whatever you wish (including commercial use), but all distributions (modified or otherwise) must be under the same license, contain the source code (with changes highlighted), and preserve the copyright notices.