Enhance UI rendering and add unit tests for simulation functionality

- Updated the `_render` function in `ui.py` to correctly pass the request object to `TemplateResponse`.
- Initialized `upcoming_maintenance` as a typed list in `_load_dashboard` for better type safety.
- Added new unit tests in `test_simulation.py` to cover triangular sampling and uniform distribution defaults.
- Implemented a test to ensure that running the simulation without parameters returns an empty result.
- Created a parameterized test in `test_ui_routes.py` to verify that additional UI routes render the correct templates and context.

docs/testing.md

@@ -100,6 +100,8 @@ pytest tests/e2e/ --headed
 - Run with coverage: `pytest --cov --cov-report=term` for quick baselines (use `--cov-report=html` when visualizing hotspots).
 - Target 95%+ overall coverage. Focus on historically low modules: `services/simulation.py`, `services/reporting.py`, `middleware/validation.py`, and `routes/ui.py`.
 - Recent additions include unit tests that validate Monte Carlo parameter errors, reporting fallbacks, and JSON middleware rejection paths to guard against malformed inputs.
+- Latest snapshot (2025-10-21): `pytest --cov=. --cov-report=term-missing` returns **91%** overall coverage after achieving full coverage in `routes/ui.py` and `services/simulation.py`.
+- Archive coverage artifacts by running `pytest --cov=. --cov-report=xml:reports/coverage/coverage-2025-10-21.xml --cov-report=term-missing`; the generated XML lives under `reports/coverage/` for CI uploads or historical comparisons.
 
 ## CI Integration