fix: recursive setTimeout, Strict Mode guard, isAxiosError

- Replace setInterval with recursive setTimeout to prevent overlapping async polls
- Add cancellation flag in auto-start effect for React Strict Mode double-mount
- Use isAxiosError() instead of unsafe type assertion
- Remove consumeCampaignSlug/consumeReferralCode from loginWithDeepLink (fired on every poll tick, destroying values after first 202)

src/store/auth.ts

@@ -320,8 +320,6 @@ export const useAuthStore = create<AuthState>()(
       },
 
       loginWithDeepLink: async (token) => {
-        consumeCampaignSlug();
-        consumeReferralCode();
         const response = await authApi.pollDeepLinkToken(token);
         tokenStorage.setTokens(response.access_token, response.refresh_token);
         set({