feat: rewrite moonset in Rust (gtk4-rs + gtk4-layer-shell)

Feature-parity with Python v0.2.0. Same CSS, same UI, same actions.
Single 3.1 MB binary with embedded resources (CSS, wallpaper, avatar).

Modules: power.rs, i18n.rs, config.rs, users.rs, panel.rs, main.rs
45 unit tests passing. Python sources retained as reference.

README.md

@@ -7,7 +7,7 @@ Per Keybind aufrufbares Fullscreen-Overlay mit 5 Aktionen:
 
 ## Features
 
-- GTK4 + gtk4-layer-shell (OVERLAY Layer — über Waybar)
+- Rust + gtk4-rs + gtk4-layer-shell (OVERLAY Layer — über Waybar)
 - Catppuccin Mocha Theme
 - Multi-Monitor-Support (Wallpaper auf Sekundärmonitoren)
 - Inline-Confirmation für destruktive Aktionen
@@ -18,7 +18,14 @@ Per Keybind aufrufbares Fullscreen-Overlay mit 5 Aktionen:
 ## Installation
 
 ```bash
-uv pip install .
+cargo build --release
+install -Dm755 target/release/moonset /usr/bin/moonset
+```
+
+Oder via PKGBUILD:
+
+```bash
+cd pkg && makepkg -si
 ```
 
 ## Verwendung
@@ -42,16 +49,16 @@ Konfigurationsdatei: `~/.config/moonset/moonset.toml` oder `/etc/moonset/moonset
 background_path = "/usr/share/moonarch/wallpaper.jpg"
 ```
 
-Wallpaper-Fallback: Konfiguration → `/usr/share/moonarch/wallpaper.jpg` → Package-Wallpaper
+Wallpaper-Fallback: Konfiguration → `/usr/share/moonarch/wallpaper.jpg` → eingebettetes Package-Wallpaper
 
 ## Entwicklung
 
 ```bash
 # Tests
-uv run pytest tests/ -v
+cargo test
 
-# Type-Check
-uv run pyright src/
+# Release-Build
+cargo build --release
 ```
 
 ## Teil des Moonarch-Ökosystems