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

docs/superpowers/specs/2026-07-09-kimicode-global-settings-panel-design.md

@@ -2,7 +2,7 @@
 
 ## 背景
 
-Kimi Code CLI 的 `~/.kimi-code/config.toml` 包含大量全局设置：`[thinking]`、`[loop_control]`、`[background]`、`[[permission.rules]]`、`[[hooks]]` 等。当前 Pi Switch 只暴露了 `providers` 和 `models` 的可视化编辑，其他全局配置只能通过"配置 JSON"标签页手动修改，不够便捷。
+Kimi Code CLI 的 `~/.kimi-code/config.toml` 包含大量全局设置：`[thinking]`、`[loop_control]`、`[background]`、`[[permission.rules]]`、`[[hooks]]` 等。当前 Kimi Switch 只暴露了 `providers` 和 `models` 的可视化编辑，其他全局配置只能通过"配置 JSON"标签页手动修改，不够便捷。
 
 ## 目标