feat(frontend): TypeScript-Monorepo mit Terminal-UI für Effigenix ERP

Monorepo-Setup (pnpm workspaces) mit vier shared Packages und einer TUI-App:

Shared Packages:
- @effigenix/types: TypeScript-DTOs (UserDTO, RoleDTO, AuthDTO, Enums)
- @effigenix/config: API-Konfiguration und Shared Constants
- @effigenix/validation: Zod-Schemas für Username, E-Mail und Passwort
- @effigenix/api-client: axios-Client mit JWT-Handling (proaktiver + reaktiver
  Token-Refresh), AuthInterceptor, ErrorInterceptor, Resources für auth/users/roles

TUI (apps/cli, Ink 5 / React):
- Authentication: Login/Logout, Session-Restore beim Start, JWT-Refresh
- User Management: Liste, Anlage (Zod-Inline-Validation), Detailansicht,
  Passwort ändern, Sperren/Entsperren mit ConfirmDialog
- Role Management: Liste, Detailansicht, Zuweisen/Entfernen per RoleSelectList (↑↓)
- UX: SuccessDisplay (Auto-Dismiss 3 s), ConfirmDialog (J/N),
  FormInput mit Inline-Fehlern, StatusBar mit API-URL
- Layout: Fullscreen-Modus (alternate screen buffer), Header mit eingeloggtem User
- Tests: vitest + ink-testing-library (15 Tests)

frontend/apps/cli/src/state/navigation-context.tsx

@@ -0,0 +1,77 @@
+import React, { createContext, useContext, useReducer } from 'react';
+
+export type Screen =
+  | 'login'
+  | 'main-menu'
+  | 'user-list'
+  | 'user-create'
+  | 'user-detail'
+  | 'change-password'
+  | 'role-list'
+  | 'role-detail';
+
+interface NavigationState {
+  current: Screen;
+  history: Screen[];
+  params: Record<string, string>;
+}
+
+type NavigationAction =
+  | { type: 'NAVIGATE'; screen: Screen; params?: Record<string, string> }
+  | { type: 'BACK' };
+
+function navigationReducer(state: NavigationState, action: NavigationAction): NavigationState {
+  switch (action.type) {
+    case 'NAVIGATE':
+      return {
+        current: action.screen,
+        history: [...state.history, state.current],
+        params: action.params ?? {},
+      };
+    case 'BACK': {
+      const history = [...state.history];
+      const previous = history.pop();
+      if (!previous) return state;
+      return { current: previous, history, params: {} };
+    }
+  }
+}
+
+interface NavigationContextValue {
+  current: Screen;
+  params: Record<string, string>;
+  canGoBack: boolean;
+  navigate: (screen: Screen, params?: Record<string, string>) => void;
+  back: () => void;
+}
+
+const NavigationContext = createContext<NavigationContextValue | null>(null);
+
+interface NavigationProviderProps {
+  children: React.ReactNode;
+  initialScreen?: Screen;
+}
+
+export function NavigationProvider({ children, initialScreen = 'login' }: NavigationProviderProps) {
+  const [state, dispatch] = useReducer(navigationReducer, {
+    current: initialScreen,
+    history: [],
+    params: {},
+  });
+
+  const value: NavigationContextValue = {
+    current: state.current,
+    params: state.params,
+    canGoBack: state.history.length > 0,
+    navigate: (screen, params) => dispatch({ type: 'NAVIGATE', screen, params: params ?? {} }),
+    back: () => dispatch({ type: 'BACK' }),
+  };
+
+  return <NavigationContext.Provider value={value}>{children}</NavigationContext.Provider>;
+}
+
+export function useNavigation(): NavigationContextValue {
+  const ctx = useContext(NavigationContext);
+  if (!ctx) throw new Error('useNavigation must be used within NavigationProvider');
+  return ctx;
+}