fix: feat: E2E quality gate — mobile viewports + cross-browser matrix (#1099)

Add Playwright projects for Chromium, Firefox, WebKit, iPhone 14, and
Pixel 7 viewports. Chromium runs all specs (01-07); other projects run
read-only specs (03, 06, 07) after Chromium finishes, using project
dependencies to ensure chain state exists.

Coverage audit:
- Tests 01/02 already cover /app/get-krk, /app/cheats as part of flows
- Test 03 verifies GraphQL endpoints
- Test 06 covers wallet + position dashboards
- New test 07 adds landing page and docs smoke coverage

Changes:
- playwright.config.ts: 5 projects (3 desktop browsers + 2 mobile)
- wallet-provider.ts: accept optional viewport/screen for mobile contexts
- 03, 06 specs: pass project viewport to wallet context
- 07-landing-pages.spec.ts: new spec for landing homepage + docs
- e2e.yml: timeout 600→900s for cross-browser matrix, updated comments

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.woodpecker/e2e.yml

@@ -398,12 +398,14 @@ steps:
         bash scripts/wait-for-service.sh http://caddy:8081/app/       420 caddy
         echo "=== Stack is healthy ==="
 
-  # Step 3: Run E2E tests
+  # Step 3: Run E2E tests — cross-browser matrix
+  # Chromium runs all specs (01-07), then Firefox/WebKit/mobile run read-only specs (03,06,07).
+  # The matrix is defined in playwright.config.ts via `projects`.
   - name: run-e2e-tests
     image: mcr.microsoft.com/playwright:v1.55.1-jammy
     depends_on:
       - wait-for-stack
-    timeout: 600
+    timeout: 900
     environment:
       STACK_BASE_URL: http://caddy:8081
       STACK_RPC_URL: http://caddy:8081/api/rpc
@@ -427,7 +429,7 @@ steps:
         npm config set audit false
         npm ci --no-audit --no-fund
 
-        echo "=== Running E2E tests (workers=1 to limit memory) ==="
+        echo "=== Running E2E tests — cross-browser matrix (workers=1 to limit memory) ==="
         npx playwright test --reporter=list --workers=1
 
   # Step 4: Collect artifacts