feat: add runnable simulator foundation

tests/__init__.py

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+"""Test package."""

tests/unit/test_health.py

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+from __future__ import annotations
+
+from typing import Self
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from app.config import Settings
+from app.db.pool import Database
+from app.main import create_app
+
+
+class FakeDatabase:
+    def __init__(self, ready: bool) -> None:
+        self.ready = ready
+        self.connected = False
+        self.closed = False
+
+    async def connect(self) -> None:
+        self.connected = True
+
+    async def close(self) -> None:
+        self.closed = True
+
+    async def is_ready(self) -> bool:
+        return self.ready
+
+    async def __aenter__(self) -> Self:
+        await self.connect()
+        return self
+
+    async def __aexit__(self, exc_type: object, exc: object, traceback: object) -> None:
+        await self.close()
+
+
+@pytest.mark.parametrize(("database_ready", "status_code"), [(True, 200), (False, 503)])
+async def test_health_endpoints(database_ready: bool, status_code: int) -> None:
+    database = FakeDatabase(database_ready)
+
+    def factory(settings: Settings) -> Database:
+        del settings
+        return database
+
+    application = create_app(Settings(), factory)
+    async with application.router.lifespan_context(application):
+        async with AsyncClient(
+            transport=ASGITransport(app=application, raise_app_exceptions=False),
+            base_url="http://test",
+        ) as client:
+            live = await client.get("/health/live")
+            ready = await client.get("/health/ready", headers={"X-Request-ID": "test-request"})
+
+    assert live.status_code == 200
+    assert live.json() == {"status": "ok"}
+    assert ready.status_code == status_code
+    assert ready.headers["X-Request-ID"] == "test-request"
+    assert database.connected
+    assert database.closed

tests/unit/test_logging.py

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+from __future__ import annotations
+
+import json
+import logging
+
+from app.logging import JsonFormatter
+
+
+def test_json_formatter_emits_structured_fields() -> None:
+    record = logging.LogRecord("test", logging.INFO, __file__, 1, "hello %s", ("world",), None)
+    record.request_id = "request-1"
+
+    payload = json.loads(JsonFormatter().format(record))
+
+    assert payload["message"] == "hello world"
+    assert payload["request_id"] == "request-1"
+    assert payload["level"] == "INFO"