refactor(claude-desktop): drop displayName from model route schema

Claude Desktop's new model menu reads model IDs directly and ignores the
display_name field, so a separate displayName slot added UI noise without
any product value. Collapse the routeId / model / displayName tuple down
to routeId / model, and let the route ID carry the user-visible name
through a non-editable claude- prefix rendered next to the input.

Drop display_name from ClaudeDesktopModelRoute, ClaudeDesktopDefaultRoute,
and ResolvedModelRoute on the Rust side plus the matching TS interfaces,
stop emitting it in /v1/models responses, derive route IDs from upstream
model IDs when picked via the model dropdown, and update zh/en/ja copy to
describe the new two-field layout.

src-tauri/src/provider.rs

@@ -230,9 +230,6 @@ pub enum ClaudeDesktopMode {
 pub struct ClaudeDesktopModelRoute {
     /// 真实上游模型名，只保存在 CC Switch 内部，不写入 Claude Desktop profile。
     pub model: String,
-    /// Desktop /v1/models 中显示的名称。
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub display_name: Option<String>,
     /// Claude Desktop 3P 识别的 1M 上下文能力标记。
     #[serde(rename = "supports1m", skip_serializing_if = "Option::is_none")]
     pub supports_1m: Option<bool>,