SIENTIAPDE-1646

Enhance orchestration configuration and documentation. Added `RUNTIME` variable to `.env.example`, updated `.gitignore` to exclude `openspec/` and `.cursor/`, and modified `README.md` to clarify queue naming conventions and runtime handling. Refactored activities to use synchronous database and email handling, improving performance and consistency. Updated test cases to reflect these changes and ensure compatibility with new activity definitions.

e2e/README.md

@@ -0,0 +1,35 @@
+# Orchestrator end-to-end tests
+
+End-to-end tests run every external dependency for real (MongoDB, Redis, PostgreSQL via testcontainers; SMTP via in-process `aiosmtpd`; Temporal via `WorkflowEnvironment.start_local()`).
+
+## Requirements
+
+- Docker (for testcontainers)
+- Python dev dependencies: `pip install -r requirements-dev.txt`
+
+## Run locally
+
+```bash
+source ./venv/bin/activate
+pytest e2e/ --override-ini testpaths=e2e -m e2e -v
+```
+
+Stop on first failure:
+
+```bash
+pytest e2e/ --override-ini testpaths=e2e -m e2e -x
+```
+
+## Coverage (separate from unit tests)
+
+```bash
+COVERAGE_FILE=.coverage.e2e pytest e2e/ --override-ini testpaths=e2e -m e2e --cov=orchestrator --cov-branch
+coverage combine .coverage .coverage.e2e
+coverage report
+```
+
+Unit tests keep the default `.coverage` file; the E2E run must set `COVERAGE_FILE=.coverage.e2e` so reports do not overwrite each other.
+
+## Scenario catalog
+
+See [scenarios.md](scenarios.md) for numbered scenarios and which test module implements each case.