chore: add release infrastructure and packaging support

Add GitHub Actions workflows for CI and release builds, packaging
scripts for Windows, macOS, Linux, and Flatpak/Snap distribution,
application icons, desktop files, and release metadata resources.

.github/workflows/rust.yml

@@ -0,0 +1,32 @@
+name: Rust
+
+on:
+  push:
+    branches: ["**"]
+  pull_request:
+    branches: ["m**"]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        rustup: [stable]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Linux build dependencies
+        run: chmod +x ./script/linux && ./script/linux
+        if: matrix.os == 'ubuntu-latest'
+
+      - name: Build
+        run: cargo build --verbose
+
+      - name: Run tests
+        run: cargo test --verbose