refactor: apply CLAUDE.md code quality improvements and add packaging

- Add #![forbid(unsafe_code)] to main.rs (issue #3)
- Replace raw ANSI escape codes with owo-colors crate (issue #2)
- Replace manual HOME path construction with dirs::home_dir() (issue #5)
- Ship umutray.service as a static file; service::install() substitutes
  the binary path at install time instead of generating the unit at runtime
- Add packaging/PKGBUILD following Arch Rust package guidelines
- Add CLAUDE.md tracking refactor tasks
- setup.rs: clean up downloaded temp files on abort/back, save launcher
  to config only after successful install, auto-start download when a
  preset has an installer_url
- util.rs: add pick_folder() using zenity/kdialog subprocesses (no rfd)
- config.rs: populate installer_url for all 6 built-in presets with
  official download URLs
- Document the Option<Option<Vec<String>>> gamescope pattern at main.rs:307

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packaging/PKGBUILD

@@ -0,0 +1,65 @@
+# Maintainer: funman300 <funman300@gmail.com>
+#
+# AUR NOTE: This PKGBUILD is kept in the source repo for convenience during
+# development. For AUR submission, move it to a separate repository and update
+# the `source` array to point to the upstream git URL instead of a local path.
+#
+# To build locally:
+#   cd packaging && makepkg -si
+#
+# To update for AUR, replace the source line with:
+#   source=("$pkgname::git+https://git.aleshym.co/funman300/umutray.git#tag=v$pkgver")
+
+pkgname=umutray
+pkgver=0.1.0
+pkgrel=1
+pkgdesc='Tray-based Wine launcher manager for Linux via umu/Proton-GE'
+arch=('x86_64')
+url='https://git.aleshym.co/funman300/umutray'
+license=('MIT')
+depends=('umu-launcher')
+makedepends=('rust' 'cargo')
+optdepends=(
+    'zenity: folder picker in setup wizard (GNOME/GTK)'
+    'kdialog: folder picker in setup wizard (KDE)'
+    'gamemode: per-game GameMode support'
+    'mangohud: per-game MangoHud overlay'
+    'gamescope: per-game Gamescope compositor'
+)
+
+# Build from the local repository. Change to the upstream URL for AUR.
+_localrepo="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+source=("$pkgname::git+file://${_localrepo}")
+sha256sums=('SKIP')
+
+prepare() {
+    cd "$pkgname"
+    export RUSTUP_TOOLCHAIN=stable
+    cargo fetch --locked --target "$(rustc -vV | sed -n 's/host: //p')"
+}
+
+build() {
+    cd "$pkgname"
+    export RUSTUP_TOOLCHAIN=stable
+    export CARGO_TARGET_DIR=target
+    cargo build --release --locked --offline
+}
+
+package() {
+    cd "$pkgname"
+
+    # Binary
+    install -Dm755 target/release/umutray "$pkgdir/usr/bin/umutray"
+
+    # App menu entry (.desktop uses /usr/bin/umutray as the exec path)
+    install -Dm644 umutray.desktop "$pkgdir/usr/share/applications/umutray.desktop"
+    sed -i "s|Exec=umutray|Exec=/usr/bin/umutray|" \
+        "$pkgdir/usr/share/applications/umutray.desktop"
+
+    # Systemd user service (static file — no runtime generation needed)
+    install -Dm644 umutray.service \
+        "$pkgdir/usr/lib/systemd/user/umutray.service"
+
+    # License
+    install -Dm644 LICENSE "$pkgdir/usr/share/licenses/$pkgname/LICENSE"
+}