Flatpak: build from source instead of repackaging debs

- Rewrite Flatpak manifest to build from source using SDK extensions
  (node22, rust-stable) with offline cargo/npm dependency caches
- Add generate-sources.sh to produce cargo-sources.json and
  node-sources.json from lock files using flatpak-builder-tools
- Vendor Node.js, protoc, and wasm-pack as archive sources with
  SHA256 verification and per-arch support
- Add SHA256 verification to vendor-node.cjs and vendor-protoc.cjs
- Rewrite update-manifest.sh to update git tag/commit and regenerate
  dependency sources
- Update Flathub CI workflow to install generators and copy source
  files
- Remove stale plugins/faker entry from package-lock.json

.github/workflows/flathub.yml

@@ -16,6 +16,16 @@ jobs:
       - name: Checkout app repo
         uses: actions/checkout@v4
 
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install source generators
+        run: |
+          pip install flatpak-node-generator tomlkit aiohttp
+          git clone --depth 1 https://github.com/flatpak/flatpak-builder-tools flatpak/flatpak-builder-tools
+
       - name: Run update-manifest.sh
         run: bash flatpak/update-manifest.sh "${{ github.event.release.tag_name }}"
 
@@ -29,8 +39,12 @@ jobs:
       - name: Copy updated files to Flathub repo
         run: |
           cp flatpak/app.yaak.Yaak.yml flathub-repo/
+          cp flatpak/app.yaak.Yaak.metainfo.xml flathub-repo/
+          cp flatpak/cargo-sources.json flathub-repo/
+          cp flatpak/node-sources.json flathub-repo/
           cp LICENSE flathub-repo/
           sed -i 's|path: \.\./LICENSE|path: LICENSE|' flathub-repo/app.yaak.Yaak.yml
+          sed -i 's|flatpak/app.yaak.Yaak.metainfo.xml|app.yaak.Yaak.metainfo.xml|' flathub-repo/app.yaak.Yaak.yml
 
       - name: Commit and push to Flathub
         working-directory: flathub-repo