fix(tracker-web): include productId in login (LoginSchema requires it)

The login form posted {email,password} but platform-service LoginSchema
requires productId, so real logins returned 400 (only the mocked e2e passed).
Send the selected product (tracker_selected_product) or the default PRODUCT_ID.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

dashboards/tracker-web/src/lib/auth-context.tsx

@@ -1,6 +1,7 @@
 'use client';
 
 import { createContext, useContext, useState, useEffect, useCallback, type ReactNode } from 'react';
+import { PRODUCT_ID } from './product-constants';
 
 interface User {
   id: string;
@@ -54,10 +55,15 @@ export function AuthProvider({ children }: { children: ReactNode }) {
   }, []);
 
   const login = useCallback(async (email: string, password: string) => {
+    // platform-service LoginSchema requires productId — use the selected product
+    // (set by the product switcher) or fall back to the default product.
+    const productId =
+      (typeof window !== 'undefined' && localStorage.getItem('tracker_selected_product')) ||
+      PRODUCT_ID;
     const res = await fetch('/api/auth/login', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ email, password }),
+      body: JSON.stringify({ email, password, productId }),
     });
     if (!res.ok) {
       const body = await res.json().catch(() => ({}));