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/09-mobile/viewport-reflow.spec.ts

@@ -0,0 +1,60 @@
+/**
+ * Phase 3 mobile — viewport reflow.
+ *
+ * Asserts the layout still works at landscape orientation, a narrow
+ * "small phone" viewport, and a "phablet" viewport. The bottom nav must
+ * remain reachable; the FAB stays centered; no horizontal overflow.
+ */
+import { test, expect } from '../../fixtures/test';
+
+const VIEWPORTS = [
+  { name: 'portrait (default Pixel 7)', width: 412, height: 915 },
+  { name: 'landscape (Pixel 7 rotated)', width: 915, height: 412 },
+  { name: 'narrow small phone', width: 320, height: 568 },
+  { name: 'phablet', width: 480, height: 1024 },
+];
+
+test.describe('Mobile — viewport reflow', () => {
+  for (const vp of VIEWPORTS) {
+    test(`bottom nav remains usable at ${vp.name} (${vp.width}×${vp.height})`, async ({ page, guest, signIn }) => {
+      const g = await guest(`Reflow_${vp.width}x${vp.height}`);
+      await signIn(page, g);
+      await page.setViewportSize({ width: vp.width, height: vp.height });
+      await page.goto('/feed');
+
+      const nav = page.locator('nav').filter({ has: page.getByRole('link', { name: 'Galerie' }) }).first();
+      const fab = page.getByRole('button', { name: 'Hochladen' });
+
+      await expect(nav).toBeVisible();
+      await expect(fab).toBeVisible();
+
+      // No horizontal overflow on <html>.
+      const overflowX = await page.evaluate(() => {
+        const html = document.documentElement;
+        return html.scrollWidth - html.clientWidth;
+      });
+      expect.soft(overflowX, 'no horizontal overflow').toBeLessThanOrEqual(1);
+
+      // FAB is roughly centered: its x-mid should be within 30% of the viewport mid.
+      const fabBox = await fab.boundingBox();
+      if (!fabBox) throw new Error('FAB has no bounding box');
+      const fabMidX = fabBox.x + fabBox.width / 2;
+      const expectedMid = vp.width / 2;
+      expect.soft(Math.abs(fabMidX - expectedMid)).toBeLessThanOrEqual(vp.width * 0.30);
+    });
+  }
+
+  test('rotation portrait → landscape preserves auth + bottom nav', async ({ page, guest, signIn }) => {
+    const g = await guest('Rotate');
+    await signIn(page, g);
+    await page.goto('/feed');
+    await expect(page.getByRole('link', { name: 'Galerie' })).toBeVisible();
+
+    await page.setViewportSize({ width: 915, height: 412 });
+    // The same nav should still be visible — no layout shift forces a re-render that loses auth.
+    await expect(page.getByRole('link', { name: 'Galerie' })).toBeVisible();
+
+    const stillAuthed = await page.evaluate(() => !!localStorage.getItem('eventsnap_jwt'));
+    expect(stillAuthed).toBe(true);
+  });
+});