E2E: fix firefox/webkit shards (need chromium) + guest Lead contract

- firefox and safari-ios shards failed at launch ("chrome-headless-shell doesn't
  exist") because global-setup.js seeds the customer cookie via chromium.launch();
  install chromium alongside firefox/webkit on those shards.
- guest Lead failed with "pixel user_data.em missing": the Pixel Lead only carries
  em via session advanced-matching, so guests have no pixel em. Drop the Lead
  user_data override so it inherits the mode-aware base (customer em+fbp / guest
  fbp only); the form email reaching CAPI is still asserted via the event_id-keyed
  check in the spec.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Vahid Kay

.github/workflows/e2e-tests.yml

@@ -231,9 +231,11 @@ jobs:
           DEBIAN_FRONTEND: noninteractive
         run: |
           npm ci
+          # global-setup.js launches chromium to seed the customer cookie, so every
+          # shard needs chromium in addition to its own engine.
           case "${{ matrix.project }}" in
-            firefox-*)         timeout 15m npx playwright install --with-deps firefox ;;
-            safari-ios-*)      timeout 15m npx playwright install --with-deps webkit ;;
+            firefox-*)         timeout 15m npx playwright install --with-deps chromium firefox ;;
+            safari-ios-*)      timeout 15m npx playwright install --with-deps chromium webkit ;;
             *privacy-sandbox*) timeout 15m npx playwright install --with-deps chromium chrome ;;
             edge-*)            timeout 15m npx playwright install --with-deps chromium msedge ;;
             *)                 timeout 15m npx playwright install --with-deps chromium ;;

tests/e2e/helpers/js/events/field-contracts.js

@@ -96,11 +96,10 @@ const EVENT_OVERLAYS = {
 
   Lead: {
     channels: ['pixel', 'capi'],
-    // Form-provided PII: present for both logged-in and guest submitters.
-    user_data: {
-      pixel: ['em', 'fbp'],
-      capi: ['em', 'fbp'],
-    },
+    // Inherit the mode-aware base user_data: the Pixel Lead only carries `em` via
+    // session advanced-matching (so customer → em+fbp, guest → fbp only). The
+    // form-submitted email is asserted to reach CAPI separately in the spec
+    // (keyed off the shared event_id), so it stays verified in both modes.
     custom_data: { pixel: [], capi: [] },
   },
 };