docs: Update README with supported architectures and AUR installation info

.github/workflows/build.yml

@@ -0,0 +1,188 @@
+name: Build Untrunc (Multi-Arch)
+
+on:
+  push:
+    branches: [ "master", "main" ]
+    tags: [ "v*" ]
+  pull_request:
+    branches: [ "master", "main" ]
+  workflow_dispatch:
+
+jobs:
+  get-ffmpeg-version:
+    name: Get Latest FFmpeg Version
+    runs-on: ubuntu-latest
+    outputs:
+      version: ${{ steps.get-version.outputs.version }}
+    steps:
+      - name: Get latest FFmpeg release
+        id: get-version
+        run: |
+          VERSION=$(curl -s https://ffmpeg.org/releases/ | grep -oP 'ffmpeg-\K[0-9]+\.[0-9]+(\.[0-9]+)?' | sort -V | tail -1)
+          echo "Latest FFmpeg version: $VERSION"
+          echo "version=$VERSION" >> $GITHUB_OUTPUT
+
+  build-linux:
+    name: Linux (${{ matrix.arch }})
+    runs-on: ubuntu-latest
+    needs: get-ffmpeg-version
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - arch: amd64
+            platform: linux/amd64
+            image: debian:12-slim
+          - arch: arm64
+            platform: linux/arm64
+            image: debian:12-slim
+          - arch: armv7
+            platform: linux/arm/v7
+            image: debian:12-slim
+          - arch: i386
+            platform: linux/386
+            image: i386/debian:12-slim
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Cache compiled FFmpeg
+        id: cache-ffmpeg
+        uses: actions/cache@v4
+        with:
+          path: ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}
+          key: ffmpeg-built-linux-${{ matrix.arch }}-${{ needs.get-ffmpeg-version.outputs.version }}
+
+      - name: Build FFmpeg inside Docker
+        if: steps.cache-ffmpeg.outputs.cache-hit != 'true'
+        run: |
+          docker run --rm --platform ${{ matrix.platform }} \
+            -v ${{ github.workspace }}:/workspace \
+            -w /workspace \
+            ${{ matrix.image }} /bin/bash -c "
+              apt-get update && \
+              apt-get install -y g++ make wget nasm xz-utils && \
+              wget -q -O /tmp/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}.tar.xz \
+                https://www.ffmpeg.org/releases/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}.tar.xz && \
+              tar xf /tmp/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}.tar.xz && \
+              mv ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}/VERSION \
+                 ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}/VERSION.bak && \
+              cd ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }} && \
+              ./configure --disable-doc --disable-programs \
+                --disable-everything --enable-decoders --disable-vdpau --enable-demuxers --enable-protocol=file \
+                --disable-avdevice --disable-swresample --disable-swscale --disable-avfilter \
+                --disable-xlib --disable-vaapi --disable-zlib --disable-bzlib --disable-lzma && \
+              make -j\$(nproc) && \
+              chown -R \$(stat -c '%u:%g' /workspace) /workspace/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}
+            "
+
+      - name: Build untrunc inside Docker
+        run: |
+          docker run --rm --platform ${{ matrix.platform }} \
+            -v ${{ github.workspace }}:/workspace \
+            -w /workspace \
+            ${{ matrix.image }} /bin/bash -c "
+              apt-get update && \
+              apt-get install -y g++ make && \
+              make FF_VER=${{ needs.get-ffmpeg-version.outputs.version }} IS_RELEASE=1 && \
+              mv untrunc untrunc-linux-${{ matrix.arch }}
+            "
+
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: untrunc-linux-${{ matrix.arch }}
+          path: untrunc-linux-${{ matrix.arch }}
+
+  build-macos:
+    name: macOS (${{ matrix.arch }})
+    runs-on: ${{ matrix.os }}
+    needs: get-ffmpeg-version
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: macos-15-intel
+            arch: x86_64
+          - os: macos-14
+            arch: arm64
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Cache compiled FFmpeg
+        id: cache-ffmpeg
+        uses: actions/cache@v4
+        with:
+          path: ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}
+          key: ffmpeg-built-macos-${{ matrix.arch }}-${{ needs.get-ffmpeg-version.outputs.version }}
+
+      - name: Install build tools
+        run: brew install nasm wget
+
+      - name: Build FFmpeg
+        if: steps.cache-ffmpeg.outputs.cache-hit != 'true'
+        run: |
+          wget -q -O /tmp/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}.tar.xz \
+            https://www.ffmpeg.org/releases/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}.tar.xz
+          tar xf /tmp/ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}.tar.xz
+          mv ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}/VERSION \
+             ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}/VERSION.bak
+          cd ffmpeg-${{ needs.get-ffmpeg-version.outputs.version }}
+          ./configure --disable-doc --disable-programs \
+            --disable-everything --enable-decoders --disable-vdpau --enable-demuxers --enable-protocol=file \
+            --disable-avdevice --disable-swresample --disable-swscale --disable-avfilter \
+            --disable-xlib --disable-vaapi --disable-zlib --disable-bzlib --disable-lzma \
+            --disable-audiotoolbox --disable-videotoolbox
+          make -j$(sysctl -n hw.logicalcpu)
+
+      - name: Build untrunc
+        run: |
+          make FF_VER=${{ needs.get-ffmpeg-version.outputs.version }} IS_RELEASE=1
+          mv untrunc untrunc-macos-${{ matrix.arch }}
+
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: untrunc-macos-${{ matrix.arch }}
+          path: untrunc-macos-${{ matrix.arch }}
+
+  release:
+    name: Create Release
+    runs-on: ubuntu-latest
+    needs: [get-ffmpeg-version, build-linux, build-macos]
+    if: startsWith(github.ref, 'refs/tags/v')
+    permissions:
+      contents: write
+    steps:
+      - name: Download Artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: artifacts
+          merge-multiple: true
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v1
+        with:
+          files: artifacts/*
+          body: |
+            ## Untrunc Release
+
+            Automated builds for **Linux** and **macOS**, compiled with **FFmpeg ${{ needs.get-ffmpeg-version.outputs.version }}** (bundled — no ffmpeg installation needed).
+
+            ### Which file to choose?
+
+            | Platform | CPU | File |
+            |---|---|---|
+            | Linux 64-bit (Intel/AMD) | x86_64 | `untrunc-linux-amd64` |
+            | Linux 64-bit (ARM, e.g. RPi 4/5) | aarch64 | `untrunc-linux-arm64` |
+            | Linux 32-bit (ARM, e.g. RPi 2/3) | armv7 | `untrunc-linux-armv7` |
+            | Linux 32-bit (Intel/AMD) | i386 | `untrunc-linux-i386` |
+            | macOS (Intel) | x86_64 | `untrunc-macos-x86_64` |
+            | macOS (Apple Silicon M1/M2/M3) | arm64 | `untrunc-macos-arm64` |
+