test: add comprehensive automated test coverage

- Vitest multi-project setup (unit / integration / component)
- Real-Postgres integration harness via in-process PGlite (TEST_DATABASE_URL
  override), migrations applied per worker; production code untouched
- Unit: routing, locale, validation/Zod schemas, metadata, mail, site-theme,
  marquee, media, portfolio helpers, plus architecture-rule tests
- Integration: Prisma data layer, API routes, and all server actions
- Component: UI primitives and form components (jsdom + Testing Library)
- 371 tests passing

tests/unit/form-data.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+
+import { isCheckedFormValue } from "@/lib/form-data";
+
+describe("isCheckedFormValue", () => {
+  it("treats standard checkbox values as checked", () => {
+    expect(isCheckedFormValue("on")).toBe(true);
+    expect(isCheckedFormValue("true")).toBe(true);
+    expect(isCheckedFormValue("1")).toBe(true);
+  });
+
+  it("treats other values as unchecked", () => {
+    expect(isCheckedFormValue("off")).toBe(false);
+    expect(isCheckedFormValue("false")).toBe(false);
+    expect(isCheckedFormValue("0")).toBe(false);
+    expect(isCheckedFormValue("")).toBe(false);
+    expect(isCheckedFormValue(null)).toBe(false);
+    expect(isCheckedFormValue("yes")).toBe(false);
+  });
+});