orders: share the merchant tidy, and fix two bugs the corpus run found (board 212)

The tidy existed but lived inside the list page, so the DETAIL page never had
it: following a row through showed "Apple" becoming "Apple Pty Ltd." Moved to
src/lib/merchant-label.ts and applied on both surfaces.

Running it over all 1,451 distinct merchant names — rather than over examples —
turned up two real defects:

  Coburger & Co                    -> "Coburger &"
  eBay Commerce Australia Pty Ltd. -> "EBay Commerce Australia"

The first strips a suffix that is part of the brand and leaves a dangling
connector. The second is the capitalisation rule firing on "starts with a
lower-case letter" when what it means is "is a bare domain" — mangling a brand
that is deliberately lower-cased. Both are now guarded, and re-running over the
full corpus reports 170 names tidied and 0 defects.

PRESENTATION ONLY. It merges nothing and must never decide two rows are the
same merchant. Amazon.in stays Amazon.in — a different marketplace with
different currency and geography, not a name variant — and there is a test
asserting it can never equal amazon.com.au. Kogan.com, GOG.com, AliExpress.com
and Catch.com.au are real brand names containing a TLD and are left alone.
Real unification is the merchant-alias bridge, ticket 176, which has already
merged what can be merged safely.

The five names that read alike after tidying (ebay/eBay/eBay Inc.,
menulog/Menulog Pty Ltd, deliveroo/Deliveroo, grab/Grab, paypal/PayPal) are
genuinely one merchant each, so reading alike is correct. Lower-case platform
SLUGS are deliberately not capitalised: "ebay" -> "Ebay" is wrong, and getting
it right is the registry's job, not the stylesheet's.

src/__tests__/unit/merchant-label.test.ts

@@ -0,0 +1,72 @@
+import { describe, expect, it } from "vitest";
+import { tidyMerchant } from "@/lib/merchant-label";
+
+/**
+ * Board 212. Every fixture below is a real `display_name` from order_feed.
+ * The cases that matter most are the ones that must NOT change: this is a
+ * presentational tidy and merging anything here would be a data error wearing
+ * a stylesheet.
+ */
+describe("tidyMerchant", () => {
+  it("capitalises a bare domain used as a name", () => {
+    expect(tidyMerchant("amazon.com.au")).toBe("Amazon.com.au");
+    expect(tidyMerchant("cdkeys.com")).toBe("Cdkeys.com");
+  });
+
+  it("NEVER merges the country marketplaces", () => {
+    // The single most important assertion in this file. Amazon.in is a
+    // different marketplace with different currency and geography, and 289
+    // orders sit behind it.
+    expect(tidyMerchant("Amazon.in")).toBe("Amazon.in");
+    expect(tidyMerchant("amazon.com.au")).not.toBe(tidyMerchant("Amazon.in"));
+  });
+
+  it("leaves real brand names that contain a TLD alone", () => {
+    for (const brand of ["Kogan.com", "GOG.com", "AliExpress.com", "Catch.com.au", "GeekBuying.com"]) {
+      expect(tidyMerchant(brand)).toBe(brand);
+    }
+  });
+
+  it("does not uppercase a deliberately lower-cased brand", () => {
+    // The bug the corpus run found: gating on "starts lower-case" rather than
+    // on "is a bare domain" turned this into "EBay Commerce Australia".
+    expect(tidyMerchant("eBay Commerce Australia Pty Ltd.")).toBe("eBay Commerce Australia");
+    expect(tidyMerchant("iRobot Australia Pty Ltd")).toBe("iRobot Australia");
+  });
+
+  it("drops trailing corporate suffixes", () => {
+    expect(tidyMerchant("Apple Pty Ltd.")).toBe("Apple");
+    expect(tidyMerchant("Microsoft Pty. Limited")).toBe("Microsoft");
+    expect(tidyMerchant("Meta Platforms, Inc.")).toBe("Meta Platforms");
+    expect(tidyMerchant("Domino's Pizza Enterprises Limited")).toBe("Domino's Pizza Enterprises");
+    expect(tidyMerchant("Blinks Labs GmbH")).toBe("Blinks Labs");
+    expect(tidyMerchant("Rasier New Zealand Limited")).toBe("Rasier New Zealand");
+  });
+
+  it("strips two suffixes when a name carries two", () => {
+    expect(tidyMerchant("Samsung Electronics Co. Ltd.")).toBe("Samsung Electronics");
+    expect(tidyMerchant("DiDi Mobility Information Technology Pte. Ltd."))
+      .toBe("DiDi Mobility Information Technology");
+  });
+
+  it("does not leave a dangling connector", () => {
+    // 'Co' is part of this brand. Stripping it produced "Coburger &".
+    expect(tidyMerchant("Coburger & Co")).toBe("Coburger & Co");
+  });
+
+  it("keeps a name that would be reduced to almost nothing", () => {
+    // "UT" is too short to stand on its own; better scruffy than cryptic.
+    expect(tidyMerchant("UT LLC")).toBe("UT LLC");
+  });
+
+  it("normalises whitespace and tolerates junk", () => {
+    expect(tidyMerchant("  Yaffa   Media  Pty Ltd ")).toBe("Yaffa Media");
+    expect(tidyMerchant("")).toBe("");
+  });
+
+  it("is idempotent", () => {
+    for (const n of ["amazon.com.au", "Apple Pty Ltd.", "Coburger & Co", "Amazon.in"]) {
+      expect(tidyMerchant(tidyMerchant(n))).toBe(tidyMerchant(n));
+    }
+  });
+});