feat: add provider-specific terminal button

Add a terminal button next to each provider card that opens a new terminal
window with that provider's specific API configuration. This allows using
different providers independently without changing the global setting.

Changes:
- Backend: Add `open_provider_terminal` command that extracts provider
  config and creates a temporary claude settings file
- Frontend: Add terminal button to provider cards with proper callback
  propagation through component hierarchy
- Support macOS (Terminal.app), Linux (gnome-terminal, konsole, etc.),
  and Windows (cmd)

Each provider gets a unique config file named `claude_<providerId>_<pid>.json`
in the temp directory, containing the provider's API configuration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/App.tsx

@@ -286,6 +286,26 @@ function App() {
     await addProvider(duplicatedProvider);
   };
 
+  // 打开提供商终端
+  const handleOpenTerminal = async (provider: Provider) => {
+    try {
+      await providersApi.openTerminal(provider.id, activeApp);
+      toast.success(
+        t("provider.terminalOpened", {
+          defaultValue: "终端已打开",
+        }),
+      );
+    } catch (error) {
+      console.error("[App] Failed to open terminal", error);
+      const errorMessage = extractErrorMessage(error);
+      toast.error(
+        t("provider.terminalOpenFailed", {
+          defaultValue: "打开终端失败",
+        }) + (errorMessage ? `: ${errorMessage}` : ""),
+      );
+    }
+  };
+
   // 导入配置成功后刷新
   const handleImportSuccess = async () => {
     try {
@@ -378,6 +398,7 @@ function App() {
                       onDuplicate={handleDuplicateProvider}
                       onConfigureUsage={setUsageProvider}
                       onOpenWebsite={handleOpenWebsite}
+                      onOpenTerminal={handleOpenTerminal}
                       onCreate={() => setIsAddOpen(true)}
                     />
                   </motion.div>