refactor: workspace restructure — contract package + pure domain ported, tests green

- bun workspaces: contract/ (Schemas = source of truth: config raw↔resolved,
  domain DTOs, HttpApi contract, API errors) + plugin/ + ui/
- pure domain moved src/{engine,art}→plugin/src/{domain,art}, types now
  imported from @rom-manager/contract and @punktfunk/plugin-kit/wire (the
  hand-copied wire.ts dies), loggers injected instead of module-global
- ui.* and devEntry dropped from the config shape (standalone server is
  gone; stale keys tolerated on decode, dropped by the next save)
- all 48 domain tests ported and green BEFORE any Effect wiring

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugin/test/libretro.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, test } from "bun:test";
+import {
+	buildUrl,
+	candidateNames,
+	LibretroProvider,
+	sanitizeName,
+} from "../src/art/libretro.js";
+import { parseTitle } from "../src/domain/titles.js";
+import { platformById } from "../src/domain/platforms.js";
+
+const snes = platformById("snes")!;
+const nswitch = platformById("switch")!;
+
+describe("libretro name handling", () => {
+	test("sanitizeName replaces the forbidden characters with underscore", () => {
+		expect(sanitizeName("Ratchet & Clank")).toBe("Ratchet _ Clank");
+		expect(sanitizeName("Where in the World?")).toBe("Where in the World_");
+	});
+
+	test("candidateNames walks exact → region → base", () => {
+		const names = candidateNames(parseTitle("Chrono Trigger (USA) (Rev 1)"));
+		expect(names[0]).toBe("Chrono Trigger (USA) (Rev 1)"); // exact
+		expect(names).toContain("Chrono Trigger (USA)"); // region-kept
+		expect(names).toContain("Chrono Trigger (Europe)"); // region-relaxed
+		expect(names.at(-1)).toBe("Chrono Trigger"); // bare
+	});
+});
+
+describe("LibretroProvider", () => {
+	test("returns the first probe hit as a portrait", async () => {
+		const hit = buildUrl(
+			snes.libretroSystem!,
+			sanitizeName("Chrono Trigger (USA)"),
+		);
+		const provider = new LibretroProvider((url) =>
+			Promise.resolve(url === hit),
+		);
+		const art = await provider.resolve(
+			snes,
+			parseTitle("Chrono Trigger (USA)"),
+		);
+		expect(art).toEqual({ portrait: hit });
+	});
+
+	test("returns null when nothing matches", async () => {
+		const provider = new LibretroProvider(() => Promise.resolve(false));
+		expect(
+			await provider.resolve(snes, parseTitle("Nonexistent Game")),
+		).toBeNull();
+	});
+
+	test("returns null for a platform with no libretro system (Switch)", async () => {
+		const provider = new LibretroProvider(() => Promise.resolve(true));
+		expect(await provider.resolve(nswitch, parseTitle("Zelda"))).toBeNull();
+	});
+});