feat: complete release readiness work

- consolidate API ownership and remove dead vendor code

- add Stripe billing, learning paths, and public CV hardening

- add migration, recovery, security, audit, and browser gates

job-tracker-ui/src/ai-usage-card.test.tsx

@@ -4,7 +4,7 @@ import { render, screen } from "@testing-library/react";
 import AiUsageCard from "./components/AiUsageCard";
 import { api } from "./api";
 
-jest.mock("./api", () => ({ api: { get: jest.fn() } }));
+jest.mock("./api", () => ({ api: { get: jest.fn(), post: jest.fn() } }));
 jest.mock("./i18n/I18nProvider", () => ({ useI18n: () => ({ t: (key: string, params?: Record<string, unknown>) => {
   const messages: Record<string, string> = {
     settingsUsageTitle: "Account usage",
@@ -14,13 +14,14 @@ jest.mock("./i18n/I18nProvider", () => ({ useI18n: () => ({ t: (key: string, par
     settingsUsageTokens: "{used} of {limit} estimated tokens",
     settingsUsageStorage: "{used} of {limit} attachment storage",
     settingsUsageReset: "AI limits reset at the start of each calendar month.",
+    settingsBillingUpgrade: "Upgrade to Premium",
   };
   return Object.entries(params ?? {}).reduce((text, [name, value]) => text.replace(`{${name}}`, String(value)), messages[key] ?? key);
 } }) }));
 
 test("shows monthly AI call and token limits", async () => {
-  (api.get as jest.Mock).mockResolvedValue({
-    data: {
+  (api.get as jest.Mock).mockImplementation((url: string) => Promise.resolve({
+    data: url === "/billing/status" ? { enabled: true, canCheckout: true, canManage: false } : {
       currentMonth: { calls: 4, estimatedTokens: 12000 },
       plan: "free",
       monthlyCallLimit: 25,
@@ -28,7 +29,7 @@ test("shows monthly AI call and token limits", async () => {
       storageUsedBytes: 50000000,
       storageLimitBytes: 250000000,
     },
-  });
+  }));
 
   render(<AiUsageCard />);
 
@@ -36,4 +37,5 @@ test("shows monthly AI call and token limits", async () => {
   expect(screen.getByText("12,000 of 100,000 estimated tokens")).toBeInTheDocument();
   expect(screen.getByText("50.0 MB of 250.0 MB attachment storage")).toBeInTheDocument();
   expect(screen.getByLabelText("Monthly AI generations used")).toHaveAttribute("aria-valuenow", "16");
+  expect(screen.getByRole("button", { name: "Upgrade to Premium" })).toBeInTheDocument();
 });