revert: roll back flatpak packaging experiment (#271 + follow-ups) (#297)

Reverts #271, #292, #293, #294, #295, #296.

The flatpak CI pipeline itself works end-to-end, but the installed bundle
surfaced three separate manifest issues during smoke-test on Wayland+NVIDIA:

1. GDK_BACKEND is not set, so without an X11 display in the sandbox GTK
   aborts with "Failed to initialize GTK".
2. libayatana-appindicator3 is not bundled in the GNOME 47 runtime, so
   libappindicator-sys panics the main thread.
3. The release binary is compiled via \`cargo build --release\` rather than
   \`cargo tauri build\`, so the \`custom-protocol\` feature is off and
   Tauri falls back to devUrl — the window opens but shows
   "Could not connect to localhost".

Rolling back so main stays on 1.43.0. A follow-up on the original PR
tracks the fixes needed before re-attempting.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/release.yml

@@ -73,7 +73,6 @@ jobs:
 
   build-macos-windows:
     needs: create-release
-    if: false # TEMP: flatpak-only test run
     permissions:
       contents: write
     strategy:
@@ -164,7 +163,6 @@ jobs:
 
   generate-manifest:
     needs: [create-release, build-macos-windows]
-    if: false # TEMP: flatpak-only test run
     runs-on: ubuntu-24.04
     permissions:
       contents: write
@@ -184,7 +182,6 @@ jobs:
 
   build-linux:
     needs: create-release
-    if: false # TEMP: flatpak-only test run
     permissions:
       contents: write
     runs-on: ubuntu-24.04
@@ -231,81 +228,6 @@ jobs:
             \( -name "*.deb" -o -name "*.rpm" -o -name "*.AppImage" \) \
             | xargs gh release upload "app-v${VERSION}" --clobber
 
-  build-flatpak:
-    needs: create-release
-    permissions:
-      contents: write
-    runs-on: ubuntu-24.04
-    container:
-      image: bilelmoussaoui/flatpak-github-actions:gnome-47
-      options: --privileged
-    steps:
-      - uses: actions/checkout@v5
-
-      # Container runs as root but the checkout is owned by the runner user;
-      # without this, any later `git` (including gh release upload's internal
-      # git probe) aborts with "dubious ownership".
-      - name: mark workspace as safe for git
-        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
-
-      - name: install source-generation tools
-        run: |
-          dnf install -y python3-pip python3-aiohttp
-          pip3 install --break-system-packages tomlkit
-
-      - name: install flatpak-builder-tools
-        run: |
-          git clone --depth=1 \
-            https://github.com/flatpak/flatpak-builder-tools.git \
-            /tmp/flatpak-builder-tools
-          # cargo generator: still a single script
-          # node generator: now a proper Python package, install via pip
-          pip3 install --break-system-packages \
-            /tmp/flatpak-builder-tools/node
-
-      - name: generate cargo offline sources
-        run: |
-          python3 /tmp/flatpak-builder-tools/cargo/flatpak-cargo-generator.py \
-            src-tauri/Cargo.lock -o packages/flatpak/cargo-sources.json
-
-      - name: generate npm offline sources
-        run: |
-          flatpak-node-generator npm package-lock.json \
-            -o packages/flatpak/npm-sources.json
-
-      - name: patch manifest for this release
-        # The `app-v*` tag only materialises when the Draft release is published,
-        # so it is not a real git ref during CI. Use the triggering `v*` tag
-        # and its commit sha directly — both exist when the workflow runs.
-        env:
-          TRIGGER_TAG: ${{ github.ref_name }}
-          TRIGGER_SHA: ${{ github.sha }}
-        run: |
-          sed -i \
-            -e "s|tag: app-v.*|tag: ${TRIGGER_TAG}|" \
-            -e "s|commit: PLACEHOLDER_COMMIT|commit: ${TRIGGER_SHA}|" \
-            -e "s|VITE_LASTFM_API_KEY=__LASTFM_KEY__|VITE_LASTFM_API_KEY=${{ secrets.VITE_LASTFM_API_KEY }}|" \
-            -e "s|VITE_LASTFM_API_SECRET=__LASTFM_SECRET__|VITE_LASTFM_API_SECRET=${{ secrets.VITE_LASTFM_API_SECRET }}|" \
-            packages/flatpak/dev.psysonic.Psysonic.yml
-
-      - uses: flatpak/flatpak-github-actions/flatpak-builder@v6
-        with:
-          bundle: Psysonic_${{ needs.create-release.outputs.package_version }}.flatpak
-          manifest-path: packages/flatpak/dev.psysonic.Psysonic.yml
-          cache-key: flatpak-${{ github.sha }}
-
-      - name: install gh CLI
-        run: dnf install -y gh
-
-      - name: upload flatpak bundle to release
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: |
-          VERSION=${{ needs.create-release.outputs.package_version }}
-          gh release upload "app-v${VERSION}" \
-            "Psysonic_${VERSION}.flatpak" \
-            --clobber
-
   # Verifies that `nix build .#psysonic` still works against the current source,
   # refreshes `nix/upstream-sources.json` (npmDepsHash) + `flake.lock`
   # (nixpkgs pin), and pushes the resulting store paths to the public Cachix
@@ -315,7 +237,6 @@ jobs:
   # The refreshed lock/hash files are committed back to `main` when they change.
   verify-nix:
     needs: create-release
-    if: false # TEMP: flatpak-only test run
     runs-on: ubuntu-24.04
     permissions:
       contents: write