feat(auth): add google sign-in onboarding flow

src/api/users.ts

@@ -1,4 +1,4 @@
-import { authFetch, buildApiError } from './client';
+import { authFetch, buildApiError, buildApiUrl } from './client';
 
 // --- Auth Endpoints ---
 
@@ -28,8 +28,72 @@ export const loginWithOtp = async (mobile: string, otp: string) => {
   if (!response.ok) throw await buildApiError(response);
   return response.json();
 };
-
-export const logoutUser = async (refreshToken: string) => {
+
+export const startGoogleLogin = () => {
+  window.location.assign(buildApiUrl("/api/users/oauth/google/start/"));
+};
+
+export type GoogleOAuthFlowResponse =
+  | {
+      status: "authenticated";
+      access: string;
+      refresh: string;
+    }
+  | {
+      status: "collect_mobile";
+      email: string;
+      first_name: string;
+      last_name: string;
+      avatar_url: string;
+    }
+  | {
+      status: "claim_required";
+      mobile: string;
+      detail?: string;
+    };
+
+export const getGoogleOAuthFlow = async (flow: string): Promise<GoogleOAuthFlowResponse> => {
+  const response = await authFetch(`/api/users/oauth/google/flow/?flow=${encodeURIComponent(flow)}`, {
+    method: "GET",
+  });
+  if (!response.ok) throw await buildApiError(response);
+  return response.json();
+};
+
+export const completeGoogleOAuthSignup = async (
+  flow: string,
+  mobile: string,
+): Promise<GoogleOAuthFlowResponse> => {
+  const response = await authFetch("/api/users/oauth/google/complete/", {
+    method: "POST",
+    body: JSON.stringify({ flow, mobile }),
+  });
+  if (!response.ok) throw await buildApiError(response);
+  return response.json();
+};
+
+export const sendGoogleOAuthClaimOtp = async (flow: string) => {
+  const response = await authFetch("/api/users/oauth/google/claim/send-otp/", {
+    method: "POST",
+    body: JSON.stringify({ flow }),
+  });
+  if (!response.ok) throw await buildApiError(response);
+  return response.json();
+};
+
+export const verifyGoogleOAuthClaim = async (
+  flow: string,
+  code: string,
+): Promise<GoogleOAuthFlowResponse> => {
+  const response = await authFetch("/api/users/oauth/google/claim/verify/", {
+    method: "POST",
+    body: JSON.stringify({ flow, code }),
+  });
+  if (!response.ok) throw await buildApiError(response);
+  return response.json();
+};
+
+export const logoutUser = async (refreshToken: string) => {
   const response = await authFetch('/api/users/logout/', {
     method: 'POST',
     body: JSON.stringify({ refresh: refreshToken })