Implement Rust shell: tray, global hotkey, overlay window

Frameless transparent always-on-top window, tray icon with toggle/quit,
persisted global hotkey (default Ctrl+Shift+K) with safe re-registration,
single-instance --toggle IPC as Wayland hotkey fallback, close-to-tray.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src-tauri/Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "kcd2-overlay"
 version = "0.1.0"
-description = "A Tauri App"
-authors = ["you"]
+description = "Game overlay with a KCD2 console command and item ID database"
+authors = ["Homer"]
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
@@ -18,8 +18,13 @@ crate-type = ["staticlib", "cdylib", "rlib"]
 tauri-build = { version = "2", features = [] }
 
 [dependencies]
-tauri = { version = "2", features = [] }
+tauri = { version = "2", features = ["tray-icon"] }
 tauri-plugin-opener = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+tauri-plugin-global-shortcut = "2"
+tauri-plugin-clipboard-manager = "2"
+tauri-plugin-store = "2"
+tauri-plugin-single-instance = "2"
+tauri-plugin-autostart = "2"