Add Linux packaging validation workflow

Author: mdheller

.github/workflows/turtle-term-linux-packaging.yml

@@ -0,0 +1,89 @@
+name: TurtleTerm Linux Packaging
+
+on:
+  pull_request:
+    paths:
+      - 'assets/sourceos/**'
+      - 'packaging/linux/**'
+      - 'packaging/scripts/**'
+      - '.github/workflows/turtle-term-linux-packaging.yml'
+  push:
+    branches:
+      - main
+    paths:
+      - 'assets/sourceos/**'
+      - 'packaging/linux/**'
+      - 'packaging/scripts/**'
+      - '.github/workflows/turtle-term-linux-packaging.yml'
+  workflow_dispatch:
+
+jobs:
+  validate-linux-package-layout:
+    name: Validate Linux package layout
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Install metadata validators
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y desktop-file-utils appstream
+
+      - name: Check native package metadata
+        run: python3 assets/sourceos/tests/test_turtle_linux_native_packaging.py
+
+      - name: Validate staged package layout
+        run: bash packaging/scripts/verify-linux-package-layout.sh
+
+  validate-debian-metadata:
+    name: Validate Debian metadata
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Install Debian packaging tools
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y lintian
+
+      - name: Validate Debian control shape
+        run: |
+          test -f packaging/linux/deb/control
+          grep -q '^Package: turtle-term$' packaging/linux/deb/control
+          grep -q '^Architecture: amd64 arm64$' packaging/linux/deb/control
+          grep -q '^Homepage: https://github.com/SourceOS-Linux/TurtleTerm$' packaging/linux/deb/control
+
+  validate-rpm-metadata:
+    name: Validate RPM metadata
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Validate RPM spec shape
+        run: |
+          test -f packaging/linux/rpm/turtle-term.spec
+          grep -q '^Name:           turtle-term$' packaging/linux/rpm/turtle-term.spec
+          grep -q '^ExclusiveArch:  x86_64 aarch64$' packaging/linux/rpm/turtle-term.spec
+          grep -q 'TURTLE_TERM_STAGE_PREFIX=%{buildroot}%{_prefix}' packaging/linux/rpm/turtle-term.spec
+          grep -q 'ai.sourceos.TurtleTerm.desktop' packaging/linux/rpm/turtle-term.spec
+
+  validate-arch-metadata:
+    name: Validate Arch metadata
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Validate PKGBUILD shape
+        run: |
+          test -f packaging/linux/arch/PKGBUILD
+          grep -q '^pkgname=turtle-term$' packaging/linux/arch/PKGBUILD
+          grep -q "arch=('x86_64' 'aarch64')" packaging/linux/arch/PKGBUILD
+          grep -q 'TURTLE_TERM_STAGE_PREFIX' packaging/linux/arch/PKGBUILD