feat: self-serve signup Phase 2 (frontend cutover) (#162)

Co-authored-by: Michael Chihlas <michael@resolutionflow.com>
Co-committed-by: Michael Chihlas <michael@resolutionflow.com>

frontend/src/store/authStore.ts

@@ -6,6 +6,7 @@ import { authApi } from '@/api/auth'
 import { identifyUser, resetAnalytics, analytics } from '@/lib/analytics'
 import { apiClient } from '@/api/client'
 import { clearCachedQuota } from '@/hooks/useCachedQuota'
+import { useBillingStore } from '@/store/billingStore'
 
 interface AuthState {
   user: User | null
@@ -85,6 +86,7 @@ export const useAuthStore = create<AuthState>()(
           localStorage.removeItem('access_token')
           localStorage.removeItem('refresh_token')
           clearCachedQuota()
+          useBillingStore.getState().reset()
           Sentry.setUser(null)
           resetAnalytics()
           set({ user: null, token: null, account: null, subscription: null, isAuthenticated: false, error: null })
@@ -117,6 +119,11 @@ export const useAuthStore = create<AuthState>()(
           identifyUser({ id: user.id, email: user.email, role: user.role, is_super_admin: user.is_super_admin, account_id: account?.id })
 
           set({ user, account, subscription, isLoading: false })
+
+          // Kick off billing-state fetch alongside auth — fire-and-forget so
+          // a billing error never breaks login. The billing store records
+          // its own error state.
+          void useBillingStore.getState().fetch()
         } catch (error: unknown) {
           const message = error instanceof Error ? error.message : 'Failed to fetch user'
           set({ error: message, isLoading: false })
@@ -124,7 +131,13 @@ export const useAuthStore = create<AuthState>()(
         }
       },
 
-      setTokens: (token: Token) => set({ token }),
+      // Storing tokens implies an active session — mark the store as
+      // authenticated so <ProtectedRoute> doesn't bounce the user back to
+      // /landing while fetchUser() is still inflight (e.g. immediately after
+      // the OAuth callback exchange). The refresh interceptor in api/client.ts
+      // also calls this; that path is already authenticated, so flipping the
+      // flag has no effect there.
+      setTokens: (token: Token) => set({ token, isAuthenticated: true }),
       clearError: () => set({ error: null }),
       setLoading: (loading: boolean) => set({ isLoading: loading }),
     }),