feat: add terminal panel components and Zustand store for state management

- Created a barrel export file for terminal panel components.
- Implemented Zustand store for managing terminal panel UI state, including visibility, active terminal, view mode, and terminal ordering.
- Added actions for opening/closing the terminal panel, setting the active terminal, changing view modes, and managing terminal order.
- Introduced selectors for accessing terminal panel state properties.

ccw/frontend/src/components/api-settings/CliSettingsModal.tsx

@@ -37,14 +37,6 @@ type ModeType = 'provider-based' | 'direct';
 
 // ========== Helper Functions ==========
 
-function safeStringifyConfig(config: unknown): string {
-  try {
-    return JSON.stringify(config ?? {}, null, 2);
-  } catch {
-    return '{}';
-  }
-}
-
 function parseConfigJson(
   configJson: string
 ): { ok: true; value: Record<string, unknown> } | { ok: false; errorKey: string } {