fix(2): F2-4 + F2-3 — n8n workflow round-trip + Playwright exception catch

F2-4 (P3/§4.3 floor — gate-blocker on Q1):
  tests/n8n/functional/test_workflow_roundtrip.py: plan §4.3 prescribed test.
    POST /rest/owner/setup with class-B run-scoped owner email+password (plan
    §4.4-B); capture auth cookie; POST /rest/workflows with a minimal Manual-
    Trigger workflow; GET /rest/workflows/<id>; assert the round-trip (id,
    name, nodes payload all preserved). Removes the prohibited 'needs owner
    setup' excuse; exercises n8n's defining persistence + retrieval surface.

F2-3 (cold-run flake on install):
  tests/n8n/test_install.py: wrap page.goto(...) in try/except PlaywrightError
    inside the retry loop so net::ERR_* / connection resets trigger a retry
    instead of an immediate test failure. Same pattern as F1e-1's exec_in_app
    poll+raise hardening.

PARITY.md updated: 3 recipe-specific tests now listed; workflow_roundtrip
called out as the plan §4.3 prescribed create+read-back; rationale for keeping
test_rest_settings / test_login_state retained.

Cold-verifiable on cc-ci (log /root/ccci-q1-n8n-r4.log):
  RECIPE=n8n cc-ci-run runner/run_recipe_ci.py
  all 5 stages PASS, deploy-count=1, head_ref=63dd3e0f==chaos-version=63dd3e0f.
  Custom tier ran 4 PASS: health_check, login_state, rest_settings, AND the
  new workflow_create_and_read_back.

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

tests/n8n/test_install.py

@@ -34,17 +34,27 @@ def test_serving_and_editor(live_app, meta):
             page = ctx.new_page()
             import time
 
+            from playwright.sync_api import Error as PlaywrightError
+
             deadline = time.time() + 120
             resp = None
             last_status = 0
+            last_err = ""
             while time.time() < deadline:
-                resp = page.goto(url, wait_until="domcontentloaded", timeout=30000)
-                last_status = resp.status if resp is not None else 0
+                try:
+                    resp = page.goto(url, wait_until="domcontentloaded", timeout=30000)
+                except PlaywrightError as e:  # net::ERR_*, transient navigation, etc. (F2-3)
+                    last_err = str(e)
+                    resp = None
+                    last_status = 0
+                else:
+                    last_status = resp.status if resp is not None else 0
                 if last_status in (200, 304):
                     break
                 time.sleep(3)
             assert resp is not None and last_status in (200, 304), (
-                f"page status {last_status} after polling — n8n route never came up"
+                f"page status {last_status} after polling — n8n route never came up "
+                f"(last error: {last_err or 'none'})"
             )
             body = page.content().lower()
             assert "n8n" in body or "<html" in body, "no n8n content served"