SIENTIAPDE-2202

SIENTIAPDE-2202 Add gateway end-to-end test suite (e2e/)

End-to-end suite at the repo root, following the Laborious/Orchestrator
pattern: numbered scenarios per topic in e2e/scenarios.md (1:1 with
test_scenario_* functions), scenario inputs as JSON, Postgres DDL mirrored
from production, `integration` marker, excluded from the default pytest run.

Every dependency runs for real: MongoDB, Redis, PostgreSQL, MinIO and NATS
via testcontainers, OPC UA servers in process (asyncua). Pods are built from
the environment like ingestor/app.py and driven one loop iteration at a time.

69 scenarios across 7 topics: slot leasing and failover, subscription reads,
NATS writes and write_status (incl. the SIENTIAPDE-2202 timestamp/quality
matrix, checked on the server and on the wire), gRPC ReadTag, active reads,
client certificates/security, pod lifecycle.

Replaces tests/functional (legacy slot v1 tests, fully commented out) and
tests/functional/test_write_e2e.py (now scenarios 3.1.x).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -287,11 +287,14 @@ pytest --cov=ingestor
 pytest --cov=ingestor --cov-report=html
 ```
 
-### Functional Tests
+### End-to-end Tests
+Every dependency runs for real (MongoDB, Redis, PostgreSQL, MinIO and NATS via testcontainers;
+OPC UA servers in process). Requires Docker; not part of the default `pytest` run.
 ```bash
-# Run functional tests
-pytest tests/functional/
+pytest e2e/ -o testpaths=e2e -m integration
 ```
+Numbered scenarios (slot leasing, reads, writes, gRPC, active reads, certificates, lifecycle):
+[`e2e/scenarios.md`](e2e/scenarios.md). Setup and layout: [`e2e/README.md`](e2e/README.md).
 
 ## 📊 Monitoring and Metrics