feat: add UI conformance and launch context

webui/playwright.conformance.config.ts

@@ -0,0 +1,47 @@
+import { existsSync, readdirSync } from "node:fs";
+import { homedir } from "node:os";
+import { join } from "node:path";
+import { chromium, defineConfig } from "@playwright/test";
+
+function chromiumExecutable(): string | undefined {
+  const configured = process.env.PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH;
+  if (configured) return configured;
+  const managed = chromium.executablePath();
+  if (existsSync(managed)) return managed;
+
+  const roots = [
+    join(homedir(), ".cache", "ms-playwright"),
+    join(homedir(), ".var", "app", "com.vscodium.codium", "cache", "ms-playwright")
+  ];
+  for (const root of roots) {
+    if (!existsSync(root)) continue;
+    const installations = readdirSync(root).filter((entry) => entry.startsWith("chromium-")).sort().reverse();
+    for (const installation of installations) {
+      const candidate = join(root, installation, "chrome-linux64", "chrome");
+      if (existsSync(candidate)) return candidate;
+    }
+  }
+  return undefined;
+}
+
+export default defineConfig({
+  testDir: "./conformance/tests",
+  snapshotPathTemplate: "{testDir}/snapshots/{arg}{ext}",
+  fullyParallel: false,
+  workers: 1,
+  reporter: "line",
+  use: {
+    baseURL: "http://127.0.0.1:4174",
+    browserName: "chromium",
+    colorScheme: "light",
+    locale: "de-DE",
+    reducedMotion: "reduce",
+    launchOptions: chromiumExecutable() ? { executablePath: chromiumExecutable() } : undefined
+  },
+  webServer: {
+    command: "npm run dev:conformance",
+    url: "http://127.0.0.1:4174",
+    reuseExistingServer: false,
+    timeout: 120_000
+  }
+});