feat(claude-desktop): add 3P provider switching with proxy gateway

Adds a new ClaudeDesktop AppType that writes Claude Desktop's third-party
inference profile under configLibrary/, sharing _meta.json with other
launchers (Ollama-compatible) so cc-switch can coexist with them.

Two switch modes:
- direct: provider already exposes claude-* / anthropic/claude-* model
  ids on Anthropic Messages, Claude Desktop connects to it directly.
- proxy: cc-switch's local proxy acts as the inference gateway,
  presenting only claude-* route names to Claude Desktop and mapping
  them to real upstream models. Required after Anthropic restricted
  Claude Desktop to claude-family ids.

Backend:
- New module claude_desktop_config with snapshot/rollback, official seed
  bypass, /claude-desktop/v1/{models,messages} routes, and a single
  source of truth for default proxy routes.
- Gateway token persisted in SQLite, validated on every proxied request.
- get_claude_desktop_status surfaces drift signals (stale models,
  missing routes, proxy stopped, base URL mismatch, missing token).

Frontend:
- Slim ClaudeDesktopProviderForm independent from ProviderForm,
  controlled by a top-level appId guard.
- ProviderList banner consumes the status query (5s polling) and
  renders actionable diagnostics.
- ClaudeDesktopRouteToggle in the header to start/stop the local
  gateway without touching takeover state.
- Three-locale i18n synchronised.

src-tauri/src/database/dao/providers_seed.rs

@@ -10,6 +10,8 @@
 
 use crate::app_config::AppType;
 
+pub(crate) const CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID: &str = "claude-desktop-official";
+
 /// 单条官方供应商种子定义。
 pub(crate) struct OfficialProviderSeed {
     pub id: &'static str,
@@ -22,7 +24,7 @@ pub(crate) struct OfficialProviderSeed {
     pub settings_config_json: &'static str,
 }
 
-/// Claude / Codex / Gemini 三个应用的官方预设。
+/// Claude / Claude Desktop / Codex / Gemini 的官方预设。
 ///
 /// id 固定，便于幂等检查；name 直接用英文原名（与前端预设一致），不做 i18n。
 pub(crate) const OFFICIAL_SEEDS: &[OfficialProviderSeed] = &[
@@ -36,6 +38,16 @@ pub(crate) const OFFICIAL_SEEDS: &[OfficialProviderSeed] = &[
         // 空 env 让用户走 Claude CLI 默认认证流程
         settings_config_json: r#"{"env":{}}"#,
     },
+    OfficialProviderSeed {
+        id: CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID,
+        app_type: AppType::ClaudeDesktop,
+        name: "Claude Desktop Official",
+        website_url: "https://claude.ai/download",
+        icon: "anthropic",
+        icon_color: "#D4915D",
+        // 空 env 只是占位；切换该 provider 时会恢复 Claude Desktop 1P 模式
+        settings_config_json: r#"{"env":{}}"#,
+    },
     OfficialProviderSeed {
         id: "codex-official",
         app_type: AppType::Codex,
@@ -64,3 +76,19 @@ pub(crate) const OFFICIAL_SEEDS: &[OfficialProviderSeed] = &[
 pub(crate) fn is_official_seed_id(id: &str) -> bool {
     OFFICIAL_SEEDS.iter().any(|seed| seed.id == id)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn official_seeds_include_claude_desktop() {
+        let seed = OFFICIAL_SEEDS
+            .iter()
+            .find(|seed| seed.id == CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID)
+            .expect("claude desktop official seed");
+
+        assert_eq!(seed.app_type, AppType::ClaudeDesktop);
+        assert!(is_official_seed_id(CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID));
+    }
+}

src-tauri/src/database/mod.rs

@@ -32,6 +32,7 @@ mod schema;
 mod tests;
 
 // DAO 类型导出供外部使用
+pub(crate) use dao::providers_seed::CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID;
 pub use dao::FailoverQueueItem;
 
 use crate::config::get_app_config_dir;