feat: v0.2.0 - add system tray, clean up unused role field

- Replace text '+' icon with centered SVG plus icon for the add-provider button
- Add system tray: minimize-to-tray and quit-from-tray menu (minimize hides window, close exits app)
- Remove unused model role field (no functional effect, only stored/displayed)
- Fix multiple providers showing as active in Kimi Code mode: only the default_model's provider is marked active
- Copy /reload to clipboard after provider switch as a convenience hint
- Bump version to 0.2.0

src-tauri/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "kimiswitch"
-version = "0.1.0"
-description = "Pi Switch - model config manager"
+version = "0.2.0"
+description = "Kimi Switch - model config manager"
 authors = ["you"]
 edition = "2021"
 
@@ -9,7 +9,7 @@ edition = "2021"
 tauri-build = { version = "2.0.0", features = [] }
 
 [dependencies]
-tauri = { version = "2.0.0", features = [] }
+tauri = { version = "2.0.0", features = ["tray-icon"] }
 tauri-plugin-opener = "2.0.0"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"