feat(download page): Add nightly version Flatpak option

Author: mndscp

content/pages/download.md

@@ -82,7 +82,7 @@ versions:
           file_url: https://github.com/mixxxdj/mixxx/archive/2.5.zip
         - slug: source
           name: 2.5.6 release
-          file_url: https://github.com/mixxxdj/mixxx/archive/2.5.6.tar.gz  
+          file_url: https://github.com/mixxxdj/mixxx/archive/2.5.6.tar.gz
   beta:
     name: 2.6-beta
     release_announcement: /news/2025-05-11-mixxx-2_6_beta-released
@@ -134,7 +134,7 @@ versions:
         packages:
         - slug: source
           name: 2.6 branch
-          file_url: https://github.com/mixxxdj/mixxx/archive/2.6.zip  
+          file_url: https://github.com/mixxxdj/mixxx/archive/2.6.zip
   testing:
     name: 2.7-alpha
     title: Development Snapshots
@@ -181,6 +181,25 @@ versions:
           Alternatively, you can also use an [AUR helper](https://wiki.archlinux.org/index.php/AUR_helpers) to make the installation more straightforward.
         note: |
           **The AUR is an untrusted source.** Although the `mixxx-git` package is maintained by the Mixxx development team, you should always read the `PKGBUILD` of each AUR package you install to make sure it doesn't contain malicious code.
+      - slug: flatpak
+        os: Flatpak (any Linux distribution)
+        text: |
+          The development version of Mixxx is available for all Linux distributions as a Flatpak from the official Mixxx Flatpak repository.
+          Add the repository by running:
+
+              flatpak remote-add --if-not-exists mixxx https://downloads.mixxx.org/flatpak/repo.flatpakrepo
+
+          Then, install the development version Flatpak like this:
+
+              flatpak install mixxx org.mixxx.Mixxx nightly
+
+          To run the development version Flatpak:
+
+              flatpak run org.mixxx.Mixxx//nightly
+
+          **Note:** When migrating from a distribution package or Mixxx built from source code, Mixxx Flatpak will not automatically recover your previous settings and database. Please refer to the [instructions in the manual](https://manual.mixxx.org/latest/chapters/advanced_topics#migrate-your-mixxx-library-and-settings-to-flatpak).
+
+          If you encounter issues with file or device permissions, please refer to the [Mixxx Flatpak repository](https://github.com/flathub/org.mixxx.Mixxx/issues) first.
       - slug: source
         name: Source Code
         icon: terminal.svg