test(api): achieve 100% coverage across all routes, middleware, and services

- Add full test suite for frontend.ts (POST /log and POST /error)
- Add error-path tests to all route handlers to cover catch blocks
  triggered by Prisma rejections
- Add non-Error throw tests to cover the `new Error(String(error))`
  ternary false branch in middleware, services, and route catch handlers
- Suppress unreachable outer catch in about.ts with v8 ignore (fetchReleases
  swallows all errors internally, making the outer catch genuinely dead code)

apps/api/test/routes/auth.spec.ts

@@ -113,5 +113,14 @@ describe("auth route", () => {
       const location = res.headers.get("Location") ?? "";
       expect(location).toContain("error=auth_failed");
     });
+
+    it("redirects with error when callback throws a non-Error value", async () => {
+      const { app, exchangeCode } = await makeApp();
+      exchangeCode.mockRejectedValueOnce("raw string error");
+      const res = await app.fetch(new Request("http://localhost/auth/callback?code=bad_code"));
+      expect(res.status).toBe(302);
+      const location = res.headers.get("Location") ?? "";
+      expect(location).toContain("error=auth_failed");
+    });
   });
 });