Clean up markdown of HTML entities too

Closes #3006

app/utils/string.test.ts

@@ -1,5 +1,9 @@
 import { describe, expect, test } from "vitest";
-import { pathnameFromPotentialURL, truncateBySentence } from "./strings";
+import {
+	pathnameFromPotentialURL,
+	removeMarkdown,
+	truncateBySentence,
+} from "./strings";
 
 describe("pathnameFromPotentialURL()", () => {
 	test("Resolves path name from valid URL", () => {
@@ -44,3 +48,30 @@ describe("truncateBySentence()", () => {
 		expect(truncateBySentence(text, 20)).toBe("First line");
 	});
 });
+
+describe("removeMarkdown()", () => {
+	test("Decodes   entities and collapses runs", () => {
+		const text = "     Global Gauntlet is an event";
+		expect(removeMarkdown(text)).toBe("Global Gauntlet is an event");
+	});
+
+	test("Decodes common named HTML entities", () => {
+		expect(removeMarkdown("Tom & Jerry <3 "hi"")).toBe(
+			'Tom & Jerry <3 "hi"',
+		);
+	});
+
+	test("Decodes numeric HTML entities", () => {
+		expect(removeMarkdown("caf&#233; &#x26; tea")).toBe("café & tea");
+	});
+
+	test("Leaves unknown named entities untouched", () => {
+		expect(removeMarkdown("AT&amp;T &fakeentity; rules")).toBe(
+			"AT&T &fakeentity; rules",
+		);
+	});
+
+	test("Strips HTML tags and markdown emphasis", () => {
+		expect(removeMarkdown("<p>Hello **world**!</p>")).toBe("Hello world!");
+	});
+});