feat(site): tighten proof, contact, and inquiry delivery

Lead with Batch on the home page, drop the product changelog, add a
domain note, and stop reporting success when SMTP fails.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/contact/schema.test.ts

@@ -1,6 +1,7 @@
 import assert from "node:assert/strict";
 import { describe, it } from "node:test";
 import { validateInquiry } from "./schema.ts";
+import { offerIds } from "../../content/offer-ids.ts";
 
 describe("validateInquiry", () => {
   const valid = {
@@ -37,4 +38,24 @@ describe("validateInquiry", () => {
     assert.equal(result.ok, true);
     if (result.ok) assert.equal(result.data.company, undefined);
   });
+
+  it("accepts every published offer id", () => {
+    for (const topic of offerIds) {
+      const result = validateInquiry({ ...valid, topic });
+      assert.equal(result.ok, true);
+      if (result.ok) assert.equal(result.data.topic, topic);
+    }
+  });
+
+  it("rejects an unknown topic", () => {
+    const result = validateInquiry({ ...valid, topic: "casino" });
+    assert.equal(result.ok, false);
+    if (!result.ok) assert.equal(result.field, "topic");
+  });
+
+  it("treats a blank topic as omitted", () => {
+    const result = validateInquiry({ ...valid, topic: "  " });
+    assert.equal(result.ok, true);
+    if (result.ok) assert.equal(result.data.topic, undefined);
+  });
 });