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>

e2e/README.md

@@ -0,0 +1,48 @@
+# OPC Gateway end-to-end tests
+
+End-to-end tests run every external dependency for real (MongoDB, Redis, PostgreSQL, MinIO and
+NATS via testcontainers; OPC UA servers in process with asyncua) and build each gateway pod from
+the environment exactly like `ingestor/app.py` does.
+
+## Requirements
+
+- Docker (for testcontainers), with the reaper disabled once per machine:
+  `echo "ryuk.disabled=true" >> ~/.testcontainers.properties` (see [scenarios.md](scenarios.md)).
+- Python dev dependencies: `pip install -r requirements.txt -r requirements-dev.txt`
+
+## Run locally
+
+```bash
+source ./venv/bin/activate
+pytest e2e/ -o testpaths=e2e -m integration
+```
+
+One topic, or stop on first failure:
+
+```bash
+pytest e2e/test_writes.py -o testpaths=e2e -m integration
+pytest e2e/ -o testpaths=e2e -m integration -x
+```
+
+The default `pytest` run only collects `tests/` (`testpaths`), so the E2E suite never runs there.
+
+## Layout
+
+| Path | Content |
+|---|---|
+| `conftest.py` | Containers (session), environment + state reset (per test), factories: `opc_servers`, `pods`, `put_slot`, `publish_command`, `client_certificate`, `opc_wire` |
+| `helpers.py` | `Pod` (one gateway pod, `tick()` = one main loop iteration), `load_scenario_input`, `wait_until`/`stays_false`, Mongo/Postgres/Redis queries, DataValue mask |
+| `opc_server.py` | In-process OPC UA server (`ns=2;s=<name>` variables, restart, secured mode, received writes) |
+| `db_schema.sql` | `sientia_data.predictions` DDL, mirrored from production |
+| `scenario_inputs/` | Slots (v2), connector and write command used by the scenarios |
+| `test_*.py` | One file per topic, `test_scenario_<topic>_<group>_<n>_*` |
+
+## Coverage (separate from unit tests)
+
+```bash
+COVERAGE_FILE=.coverage.e2e pytest e2e/ -o testpaths=e2e -m integration --cov=ingestor --cov-branch
+```
+
+## Scenario catalog
+
+See [scenarios.md](scenarios.md) for the numbered scenarios and which test implements each one.