Make font selection show a live preview on hover; move its code to the backend (#3487)

* Remove FontInput.svelte

* Move font picking to the backend

* Fix Text tool font choice style turning to "-" on font that doesn't support previous style

frontend/src/io-managers/fonts.ts

@@ -0,0 +1,44 @@
+import { type Editor } from "@graphite/editor";
+import { TriggerFontCatalogLoad, TriggerFontDataLoad } from "@graphite/messages";
+
+type ApiResponse = { family: string; variants: string[]; files: Record<string, string> }[];
+
+const FONT_LIST_API = "https://api.graphite.art/font-list";
+
+export function createFontsManager(editor: Editor) {
+	// Subscribe to process backend events
+	editor.subscriptions.subscribeJsMessage(TriggerFontCatalogLoad, async () => {
+		const response = await fetch(FONT_LIST_API);
+		const fontListResponse = (await response.json()) as { items: ApiResponse };
+		const fontListData = fontListResponse.items;
+
+		const catalog = fontListData.map((font) => {
+			const styles = font.variants.map((variant) => {
+				const weight = variant === "regular" || variant === "italic" ? 400 : parseInt(variant, 10);
+				const italic = variant.endsWith("italic");
+				const url = font.files[variant].replace("http://", "https://");
+
+				return { weight, italic, url };
+			});
+			return { name: font.family, styles };
+		});
+
+		editor.handle.onFontCatalogLoad(catalog);
+	});
+
+	editor.subscriptions.subscribeJsMessage(TriggerFontDataLoad, async (triggerFontDataLoad) => {
+		const { fontFamily, fontStyle } = triggerFontDataLoad.font;
+
+		try {
+			if (!triggerFontDataLoad.url) throw new Error("No URL provided for font data load");
+			const response = await fetch(triggerFontDataLoad.url);
+			const buffer = await response.arrayBuffer();
+			const data = new Uint8Array(buffer);
+
+			editor.handle.onFontLoad(fontFamily, fontStyle, data);
+		} catch (error) {
+			// eslint-disable-next-line no-console
+			console.error("Failed to load font:", error);
+		}
+	});
+}