chore(ci): Add flatter to host Flatpak repo on GitHub Pages (#76)

* chore(ci): Add flatter to host Flatpak repo on GitHub Pages

- Update release.yml to not upload .flatpak file to releases
- Create flatter.yml to automate building and hosting of Flatpak via GitHub pages using andyholmes/flatter
- Add nightly branch for main pushes and stable branch for releases
- Update README.md with the new Flatpak installation instructions

Co-authored-by: arabianq <55220741+arabianq@users.noreply.github.com>

* Potential fix for pull request finding 'CodeQL / Workflow does not contain permissions'

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

.github/workflows/flatter.yml

@@ -0,0 +1,66 @@
+name: Flatter
+
+on:
+  push:
+    branches: [main, master]
+  release:
+    types: [published]
+  workflow_dispatch:
+
+jobs:
+  flatter:
+    name: Flatter
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    container:
+      image: ghcr.io/andyholmes/flatter/freedesktop:24.08
+      options: --privileged
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup GPG
+        id: gpg
+        uses: crazy-max/ghaction-import-gpg@v6
+        with:
+          gpg_private_key: ${{ secrets.GPG_PRIVATE_KEY }}
+          passphrase: ${{ secrets.GPG_PASSPHRASE }}
+
+      - name: Set Default Branch
+        id: set_branch
+        run: |
+          if [ "${{ github.event_name }}" == "release" ]; then
+            echo "branch=stable" >> $GITHUB_OUTPUT
+          else
+            echo "branch=nightly" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Modify Manifest
+        run: |
+          echo "default-branch: ${{ steps.set_branch.outputs.branch }}" >> packages/flatpak/ru.arabianq.pwsp.yaml
+
+      - name: Build Flatpak
+        uses: andyholmes/flatter@main
+        with:
+          files: packages/flatpak/ru.arabianq.pwsp.yaml
+          gpg-sign: ${{ steps.gpg.outputs.fingerprint }}
+          upload-bundles: false
+          upload-pages-artifact: true
+
+  deploy:
+    name: Deploy to GitHub Pages
+    runs-on: ubuntu-latest
+    needs: flatter
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+
+    steps:
+      - name: GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

.github/workflows/release.yml

@@ -174,10 +174,3 @@ jobs:
           cache: true
           branch: master
           build-bundle: true
-
-      - name: Upload Flatpak to release
-        uses: softprops/action-gh-release@v2
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          tag_name: ${{ needs.prepare.outputs.tag }}
-          files: ru.arabianq.pwsp.flatpak

README.md

@@ -52,6 +52,28 @@ three main components:
 You can download pre-built binaries and .deb packages from
 the [releases page](https://github.com/arabianq/pipewire-soundpad/releases).
 
+## **Flatpak**
+
+You can install PWSP via Flatpak from our custom repository hosted on GitHub Pages.
+
+Add the repository:
+
+```bash
+flatpak remote-add --user --if-not-exists arabianq-repo https://arabianq.github.io/pipewire-soundpad/index.flatpakrepo
+```
+
+Install the stable version:
+
+```bash
+flatpak install --user arabianq-repo ru.arabianq.pwsp//stable
+```
+
+Or install the nightly version (latest commit to `main`):
+
+```bash
+flatpak install --user arabianq-repo ru.arabianq.pwsp//nightly
+```
+
 ## **Fedora Linux (and derivatives)**
 
 If you're using Fedora, you can install PWSP from a dedicated repository using DNF.