feat(mui): theme.ts with light/dark palettes, brand fonts, data-theme selector

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/theme.test.ts

@@ -0,0 +1,28 @@
+import { describe, it, expect } from "vitest";
+import { theme } from "./theme";
+
+describe("MUI theme", () => {
+  it("uses the brand fonts", () => {
+    expect(theme.typography.fontFamily).toContain("Plus Jakarta Sans");
+    expect(String(theme.typography.h1.fontFamily)).toContain("Urbanist");
+  });
+
+  it("maps the brand red per color scheme", () => {
+    expect(theme.colorSchemes.light.palette.primary.main).toBe("#c73030");
+    expect(theme.colorSchemes.dark.palette.primary.main).toBe("#d63031");
+  });
+
+  it("maps the refreshed light canvas + paper", () => {
+    expect(theme.colorSchemes.light.palette.background.default).toBe("#f4f3f1");
+    expect(theme.colorSchemes.light.palette.background.paper).toBe("#ffffff");
+  });
+
+  it("maps semantic colors per scheme", () => {
+    expect(theme.colorSchemes.light.palette.error.main).toBe("#b91c1c");
+    expect(theme.colorSchemes.dark.palette.success.main).toBe("#22c55e");
+  });
+
+  it("uses the base radius of 10", () => {
+    expect(theme.shape.borderRadius).toBe(10);
+  });
+});