feat: add Tool Search domain restriction bypass with active-installation patching

Resolve the active `claude` command from PATH and apply an equal-length
byte patch to remove the domain whitelist check. Backups are stored in
~/.cc-switch/toolsearch-backups/ (SHA-256 of path) so they survive
Claude Code version upgrades. The patch auto-reapplies on app startup
when the setting is enabled.

Frontend checks PatchResult.success and rolls back the setting on failure.

src-tauri/src/settings.rs

@@ -181,6 +181,9 @@ pub struct AppSettings {
     /// 是否跳过 Claude Code 初次安装确认
     #[serde(default)]
     pub skip_claude_onboarding: bool,
+    /// 是否解除 Tool Search 域名限制
+    #[serde(default)]
+    pub tool_search_bypass: bool,
     /// 是否开机自启
     #[serde(default)]
     pub launch_on_startup: bool,
@@ -286,6 +289,7 @@ impl Default for AppSettings {
             minimize_to_tray_on_close: true,
             enable_claude_plugin_integration: false,
             skip_claude_onboarding: false,
+            tool_search_bypass: false,
             launch_on_startup: false,
             silent_startup: false,
             enable_local_proxy: false,