feat(#415): theme fix, AuthDivider, SessionExpiryWarning components

- AUTH-014: Fix theme storage key (jarvis-theme -> mosaic-theme)
- AUTH-016: Create AuthDivider component with customizable text
- AUTH-019: Create SessionExpiryWarning floating banner (PDA-friendly, blue)
- Fix lint errors in LoginForm, OAuthButton from parallel agents
- Sync pnpm-lock.yaml for recharts dependency

Refs #415

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/components/auth/AuthDivider.test.tsx

@@ -0,0 +1,27 @@
+import { describe, it, expect } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { AuthDivider } from "./AuthDivider";
+
+describe("AuthDivider", (): void => {
+  it("should render with default text", (): void => {
+    render(<AuthDivider />);
+    expect(screen.getByText("or continue with email")).toBeInTheDocument();
+  });
+
+  it("should render with custom text", (): void => {
+    render(<AuthDivider text="or sign up" />);
+    expect(screen.getByText("or sign up")).toBeInTheDocument();
+  });
+
+  it("should render a horizontal divider line", (): void => {
+    const { container } = render(<AuthDivider />);
+    const line = container.querySelector("span.border-t");
+    expect(line).toBeInTheDocument();
+  });
+
+  it("should apply uppercase styling to text", (): void => {
+    const { container } = render(<AuthDivider />);
+    const textWrapper = container.querySelector(".uppercase");
+    expect(textWrapper).toBeInTheDocument();
+  });
+});