feat(e2e): Playwright suite — 134 tests across 9 spec areas + UA matrix

Adds an end-to-end Playwright test suite under e2e/ that spins up an
isolated docker-compose stack (Postgres :55432, Caddy :3101, backend with
EVENTSNAP_TEST_MODE=1, SvelteKit adapter-node frontend) and exercises the
SvelteKit app against the real Rust backend.

Phase 1 — happy paths covering every documented USER_JOURNEYS.md flow:
  01-auth/      join, recover, admin login, leave event, PIN lockout
  02-upload/    gallery picker (API path), rate-limit + admin toggle
  03-feed/      like/comment SSE, filters, SSE reconnect on visibility
  04-host/      event lock API, ban/unban, promote
  05-admin/     config validation, foundational authz guards, stats
  06-export/    /export status + download stub
  __smoke/      cross-UA happy-path (runs on every UA project)

Phase 2 — adversarial + browser chaos:
  07-adversarial/  XSS payloads (6 × display name path), SQLi shapes,
                   length / encoding / RTL override / NUL byte;
                   file-upload boundaries (ELF body claimed as JPEG,
                   oversize vs max_image_size_mb, zero-byte, NUL
                   filename, path-traversal, SVG-with-script);
                   JWT alg:none, signature/payload tamper, expired
                   session, PIN brute-force (serial + parallel),
                   admin password brute-force; deep authz (cross-user
                   delete, banned user across like/comment/feed-read,
                   host→admin escalation); small-scale DDoS (20× /join,
                   10MB comment body, 10 concurrent SSE).
  08-browser-chaos/ localStorage / sessionStorage / cookie purge,
                    IndexedDB drop mid-session, offline → reconnect,
                    slow-3G, 503 flakes, 429 with no retry storm,
                    multi-tab same/different user, no-JS, hostile CSS,
                    clock skew ±1h / -2d, localStorage quota exhausted.

Phase 3 — mobile gestures (runs only on chromium-mobile / Pixel 7):
  09-mobile/    touch-target ≥44px audit, env(safe-area-inset-bottom)
                structural check, long-press (FeedListCard → ContextSheet,
                quick-tap negation, click-suppression), double-tap
                (feed card like + lightbox heart-burst, via synthetic
                pointer events to bypass the first-tap-fires-click trap),
                viewport reflow (portrait/landscape/narrow/phablet),
                plus fixme stubs documenting planned gestures (swipe
                lightbox L/R, swipe-down dismiss, pull-to-refresh,
                long-press-comment).

Cross-UA matrix (chromium-engine projects run @smoke only):
  chromium-pixel7, chromium-galaxy-s22, samsung-internet (Samsung UA
  emulation on Galaxy viewport), edge-android, plus webkit-iphone,
  chrome-ios, firefox-android, firefox-desktop — the latter four need
  libavif16 on the host (Playwright dep) but the configs are in place.

Infrastructure:
  - fixtures/test.ts central test.extend (api, db, adminToken, guest,
    host, signIn). Per-test DB truncate via the dev-only POST
    /admin/__truncate route, gated by EVENTSNAP_TEST_MODE=1.
  - helpers/sse-listener.ts, helpers/upload-client.ts (Node-side
    multipart for adversarial file-upload tests + JPEG/PNG/ELF magic
    constants), helpers/touch.ts (longPress / doubleTap / swipe /
    inlineStyle / computedStyle).
  - 10 page objects covering every route + UploadSheet/Lightbox.
  - global-setup waits for /health, logs in admin, disables every
    rate-limit and quota toggle.
  - .github/workflows/e2e.yml: PR check runs chromium-desktop + the
    smoke matrix in parallel, uploads playwright-report/ and traces on
    failure.

Findings the suite surfaces as live `[finding]` warnings (not silenced):
  1. /admin/login has no rate-limit or lockout (bcrypt cost only).
  2. PIN-attempt counter races under parallel /recover requests.
  3. Zero-byte uploads pass /api/v1/upload.
  4. SVG-with-script can pass the magic-byte check (consider CSP +
     X-Content-Type-Options on /media/*).

Stack-internal docs live in e2e/README.md (UA tier table, Samsung
Internet escalation tiers A/B/C, debugging tips, roadmap).

Final tally: 134 passed / 0 failed / 9 skipped (test.fixme stubs for
not-yet-shipped gestures and one UI-upload-flow investigation).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

e2e/specs/08-browser-chaos/storage-purge.spec.ts

@@ -0,0 +1,92 @@
+/**
+ * Phase 2 browser chaos — what happens when the browser drops state mid-session?
+ *
+ * Real users: Safari ITP, "Clear browsing data", incognito mode expiring,
+ * extensions that wipe storage on tab close. The app must NEVER white-screen
+ * or expose other users' data when its own state vanishes.
+ */
+import { test, expect } from '../../fixtures/test';
+import { readStorage, clearLocalStorage, clearAllStorage } from '../../helpers/storage-helpers';
+
+test.describe('Browser chaos — storage purge', () => {
+  test('localStorage.clear() mid-session → next nav goes to /join, no crash', async ({ page, guest, signIn }) => {
+    const g = await guest('Purge1');
+    await signIn(page, g);
+    await page.goto('/feed');
+    await expect(page.getByRole('link', { name: 'Galerie' })).toBeVisible();
+
+    // Listen for any unhandled page errors so a crash is visible.
+    const errors: Error[] = [];
+    page.on('pageerror', (e) => errors.push(e));
+
+    await clearLocalStorage(page);
+    await page.goto('/feed');
+
+    // The app may redirect to /join, render an empty feed with a "sign in" prompt, or
+    // surface the join screen inline. Any of these is fine — the assertion is "no crash".
+    expect(errors.filter((e) => !e.message.includes('AbortError'))).toHaveLength(0);
+
+    // Eventually the user lands somewhere they can recover from.
+    const url = new URL(page.url());
+    expect(['/join', '/feed', '/recover', '/']).toContain(url.pathname);
+  });
+
+  test('cookies cleared mid-session — JWT in localStorage still works (no cookie dependency)', async ({ page, guest, signIn }) => {
+    const g = await guest('Purge2');
+    await signIn(page, g);
+    await page.goto('/feed');
+
+    await page.context().clearCookies();
+
+    // The api.ts client reads from localStorage, not cookies, so a /me/context call should still work.
+    const stillAuthed = await page.evaluate(async () => {
+      const res = await fetch('/api/v1/me/context', {
+        headers: { Authorization: `Bearer ${localStorage.getItem('eventsnap_jwt')}` },
+      });
+      return res.status;
+    });
+    expect(stillAuthed).toBe(200);
+  });
+
+  test('sessionStorage cleared has no effect on auth (auth lives in localStorage)', async ({ page, guest, signIn }) => {
+    const g = await guest('Purge3');
+    await signIn(page, g);
+    await page.goto('/feed');
+
+    await page.evaluate(() => sessionStorage.clear());
+    await page.reload();
+
+    const storage = await readStorage(page);
+    expect(storage.jwt).toBeTruthy(); // localStorage survived
+    await expect(page.getByRole('link', { name: 'Galerie' })).toBeVisible();
+  });
+
+  test('clearAllStorage on /admin forces re-login', async ({ page, api }) => {
+    const adminJwt = await api.adminLogin();
+    await page.goto('/');
+    await page.evaluate((j) => localStorage.setItem('eventsnap_jwt', j), adminJwt);
+    await page.goto('/admin');
+
+    await clearAllStorage(page);
+
+    await page.goto('/admin');
+    // The admin layout should bounce them to /admin/login when the JWT is gone.
+    await page.waitForURL(/admin\/login|join/, { timeout: 5_000 });
+  });
+
+  test('PIN survives clearAuth (intentional per auth.ts comment)', async ({ page, guest, signIn }) => {
+    const g = await guest('PurgePin');
+    await signIn(page, g);
+    await page.goto('/account');
+
+    // Simulate clearAuth() — clears JWT + user_id but keeps PIN so the user can recover.
+    await page.evaluate(() => {
+      localStorage.removeItem('eventsnap_jwt');
+      localStorage.removeItem('eventsnap_user_id');
+    });
+    const remaining = await readStorage(page);
+    expect(remaining.jwt).toBeNull();
+    expect(remaining.userId).toBeNull();
+    expect(remaining.pin).toBe(g.pin);
+  });
+});