test(conformance): guard Malayalam heading links against joiner loss

Extend readmeConsistency.test.ts with a Malayalam case mirroring the
existing Persian one, addressing the P2 review finding on #6383. The
update heading's U+200C is written as an explicit escape so an editor
cannot strip it invisibly; verified the test fails when the joiner is
removed from README_ml.md.

npm run test:local -- tests/conformance/readmeConsistency.test.ts
passes 10/10.

Supersedes #6383 (follow-up to #6731)

Co-Authored-By: gensokyo-dev <gensokyo-dev@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/conformance/readmeConsistency.test.ts

@@ -87,6 +87,27 @@ describe("onboarding documentation product facts", () => {
       );
     }
   });
+
+  it("preserves zero-width non-joiners in Malayalam links to GitHub-rendered headings", async () => {
+    const malayalam = await readFile(
+      resolve("docs/readme/README_ml.md"),
+      "utf8",
+    );
+    // Confirmed against GitHub's rendered README, which retains U+200C. The
+    // update heading keeps exactly one joiner between അപ and ഡേറ്റ്; an
+    // editor that drops it from the heading or the fragment must fail here.
+    const zeroWidthNonJoiner = "\u200c";
+    for (const heading of [
+      `REA അപ്${zeroWidthNonJoiner}ഡേറ്റ് ചെയ്യുക`,
+      "എന്തൊക്കെ വിശകലനം ചെയ്യാം",
+      "ഉദാഹരണങ്ങൾ",
+    ]) {
+      expect(malayalam).toContain(`## ${heading}`);
+      expect(malayalam).toContain(
+        `](#${heading.toLowerCase().replaceAll(" ", "-")})`,
+      );
+    }
+  });
 });
 
 describe("published performance evidence", () => {