feat: initial ROM & emulator manager plugin (M0–M5)

A punktfunk-plugin-* package that scans ROM directories, maps them to
emulators, fetches box art, and reconciles them into the host game library
under provider id `rom-manager` — with a console-hosted web UI.

Engine (pure, unit-tested core):
- Table-driven platform registry (~25 consoles) + emulator registry with
  best-effort per-OS detection (PATH / Flatpak / known paths) and RetroArch
  core discovery.
- Scanner with disc folding (m3u/cue/gdi), archive gating, excludes.
- No-Intro title parsing + optional per-platform region dedupe.
- Security-critical quoting seam: POSIX single-quote + Windows double-quote
  with hostile-name refusal; ROM filenames never reach a shell un-quoted.
- Pure desired-state reconcile (stable external_ids, scale guard, fingerprint
  skip) → full-replace PUT /library/provider/rom-manager.

Box art (like Steam ROM Manager): SteamGridDB primary (portrait/hero/logo/
header, fuzzy match, operator API key) behind a provider seam, with keyless
libretro-thumbnails as the zero-setup fallback (`auto` default).

UI: console-hosted via the SDK `servePluginUi` (zero plugin-side auth) with a
plugin-local REST/SSE API and a self-contained React SPA (Setup / Emulators /
Games / Sync). Standalone password-gated fallback for host-only installs.

CLI: scan / detect / preview / sync / uninstall / set-password.

48 engine tests, typecheck + biome clean, SPA builds. Verified end-to-end:
scan → detect → reconcile PUT, fingerprint idempotence, and the standalone
UI serving SPA + REST.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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/engine/titles.js";
+import { platformById } from "../src/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();
+	});
+});