Fix markdown tooltips treating Rust type labels as HTML tags

Closes #3520, a regression introduced in #3488.

frontend/src/components/floating-menus/ColorPicker.svelte

@@ -566,6 +566,7 @@
 							min={0}
 							max={255}
 							minWidth={1}
+							displayDecimalPlaces={0}
 							tooltipLabel={{ r: "Red Channel", g: "Green Channel", b: "Blue Channel" }[channel]}
 							tooltipDescription="Integers 0–255."
 						/>

frontend/src/components/floating-menus/Tooltip.svelte

@@ -36,8 +36,10 @@
 	function parseMarkdown(markdown: string | undefined): string | undefined {
 		if (!markdown) return undefined;
 
+		let text = markdown.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&apos;");
+
 		return (
-			markdown
+			text
 				// .split("\n")
 				// .map((line) => line.trim())
 				// .join("\n")