ci: add build + release workflow

Build the plugin in CI with the Decky CLI on ubuntu-latest, upload the
zip as an artifact on push/PR, and publish a GitHub Release with the zip
on v* tags. Document building from source in the README.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: codingadventures

.github/workflows/build.yml

@@ -0,0 +1,51 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "v*"
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Download Decky CLI
+        run: |
+          mkdir -p "$GITHUB_WORKSPACE/cli"
+          curl -L -o "$GITHUB_WORKSPACE/cli/decky" \
+            https://github.com/SteamDeckHomebrew/cli/releases/latest/download/decky-linux-x86_64
+          chmod +x "$GITHUB_WORKSPACE/cli/decky"
+
+      - name: Build plugin
+        run: |
+          sudo -E "$GITHUB_WORKSPACE/cli/decky" plugin build \
+            --output-path "$GITHUB_WORKSPACE/out" \
+            --tmp-output-path "$GITHUB_WORKSPACE/build" \
+            "$GITHUB_WORKSPACE"
+
+      - name: Normalize output permissions
+        run: sudo chown -R "$(id -u):$(id -g)" "$GITHUB_WORKSPACE/out"
+
+      - name: Upload build artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: Decky-Framegen
+          path: out/*.zip
+          if-no-files-found: error
+
+      - name: Create GitHub Release
+        if: startsWith(github.ref, 'refs/tags/v')
+        uses: softprops/action-gh-release@v2
+        with:
+          files: out/*.zip
+          generate_release_notes: true

README.md

@@ -113,6 +113,33 @@ Dx12Upscaler=fsr31 ~/fgmod/fgmod %command%
 - **Supporting Libraries**: All required DX12/Vulkan libraries (libxess.dll, amd_fidelityfx, etc.)
 
 
+## Building From Source
+
+This plugin is built with the [Decky CLI](https://github.com/SteamDeckHomebrew/cli), which runs the frontend `rollup` build, downloads the bundled `remote_binary` assets (OptiScaler archive + FSR4 DLLs) declared in `package.json`, and packages everything into an installable zip.
+
+### In CI (recommended)
+
+A GitHub Actions workflow at [.github/workflows/build.yml](.github/workflows/build.yml) builds the plugin on every push/PR and uploads the zip as a build artifact. Pushing a `v*` tag additionally publishes a GitHub Release with the zip attached:
+
+```bash
+git tag v0.16.0
+git push origin v0.16.0
+```
+
+### Locally
+
+Requires Docker (the CLI builds inside a Linux container) and the Decky CLI binary in `./cli/decky`:
+
+```bash
+# One-time: fetch dependencies + the Decky CLI (interactive)
+.vscode/setup.sh
+
+# Build -> produces out/<plugin-name>.zip
+just build        # or: .vscode/build.sh
+```
+
+Then install the resulting zip via Decky Loader's "Install from ZIP" option in developer settings. Note: a full build cannot run on machines without Docker (e.g. stock macOS without Docker Desktop) - use the CI workflow instead.
+
 ## Credits
 
 ### Core Technologies