Remove deprecated authStore and update implementation plan progress tracking

- Deleted `authStore` in favor of updated state management and authentication handling.
- Updated `IMPLEMENTATION_PLAN.md` with revised checklist and Phase 2 completion details.

frontend/src/stores/authStore.old.ts

@@ -1,77 +0,0 @@
-import { create } from 'zustand';
-import { persist } from 'zustand/middleware';
-
-// User type - will be replaced with generated types later
-interface User {
-  id: string;
-  email: string;
-  full_name?: string;
-  is_active: boolean;
-  is_superuser: boolean;
-  organization_id?: string;
-}
-
-interface AuthState {
-  // State
-  user: User | null;
-  accessToken: string | null;
-  refreshToken: string | null;
-  isAuthenticated: boolean;
-
-  // Actions
-  setUser: (user: User) => void;
-  setTokens: (accessToken: string, refreshToken: string) => void;
-  setAuth: (user: User, accessToken: string, refreshToken: string) => void;
-  clearAuth: () => void;
-}
-
-export const useAuthStore = create<AuthState>()(
-  persist(
-    (set) => ({
-      // Initial state
-      user: null,
-      accessToken: null,
-      refreshToken: null,
-      isAuthenticated: false,
-
-      // Actions
-      setUser: (user) =>
-        set({
-          user,
-          isAuthenticated: true,
-        }),
-
-      setTokens: (accessToken, refreshToken) =>
-        set({
-          accessToken,
-          refreshToken,
-        }),
-
-      setAuth: (user, accessToken, refreshToken) =>
-        set({
-          user,
-          accessToken,
-          refreshToken,
-          isAuthenticated: true,
-        }),
-
-      clearAuth: () =>
-        set({
-          user: null,
-          accessToken: null,
-          refreshToken: null,
-          isAuthenticated: false,
-        }),
-    }),
-    {
-      name: 'auth-storage', // localStorage key
-      partialize: (state) => ({
-        // Only persist these fields
-        user: state.user,
-        accessToken: state.accessToken,
-        refreshToken: state.refreshToken,
-        isAuthenticated: state.isAuthenticated,
-      }),
-    }
-  )
-);