test(ui): Playwright RLS sweep — real-browser proof, both personas

Phase 5.5 (plan §7.5) first increment: the SSR/HTMX frontend is swept
in a real browser (official Playwright image, no host browsers) for
BOTH personas — testuser (admin) and rls-phone (restricted; Audiobooks
hidden from them via the visibility API).

Green checks: auth rejection + session establishment; admin dashboard
renders sections incl. the hidden-from-others library; restricted
dashboard renders real sections (Recently Added present — not a
vacuous landing-page pass) with ZERO hidden-library traces; search and
media payloads leak nothing for the restricted persona.

Harness lessons encoded: / is a landing page (dashboard lives at
/dashboard); the login endpoint rate-limits rapid attempts so sessions
are established once per persona and reused via storageState — a sweep
must not look like a brute-force run; getByText visibility assertions
are wrong for <option> text (library switcher) — body-textContent
assertions instead.

COVERAGE.md tracks the full 14-area sweep per the plan; the remaining
areas (reader, collections CRUD, admin matrix, upload roundtrip) are
enumerated and pending their sweep runs.

tests/ui/playwright.config.ts

@@ -0,0 +1,17 @@
+import { defineConfig } from "@playwright/test";
+
+// Full-sweep config (plan §7.5). The dev server must be up on
+// localhost:8765 (same precondition as the Go integration tests).
+// Run via the official Playwright image — see tests/ui/README.md.
+export default defineConfig({
+  testDir: ".",
+  timeout: 30_000,
+  retries: 0,
+  reporter: [["list"]],
+  use: {
+    baseURL: "http://localhost:8765",
+    trace: "retain-on-failure",
+    screenshot: "only-on-failure",
+    actionTimeout: 10_000,
+  },
+});