feat: Initialize frontend and backend structure with essential configurations

- Added TypeScript build info for frontend.
- Created Vite configuration for React application.
- Implemented pre-commit hook to run checks before commits.
- Set up PostgreSQL Dockerfile with PostGIS support and initialization scripts.
- Added database creation script for PostgreSQL with necessary extensions.
- Established Python project configuration with dependencies and development tools.
- Developed pre-commit script to enforce code quality checks for backend and frontend.
- Created PowerShell script to set up Git hooks path.

backend/tests/test_network_service.py

@@ -0,0 +1,70 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from types import SimpleNamespace
+from uuid import uuid4
+
+import pytest
+
+from backend.app.repositories import StationRepository, TrackRepository, TrainRepository
+from backend.app.services.network import get_network_snapshot
+
+
+@pytest.fixture
+def sample_entities() -> dict[str, SimpleNamespace]:
+    timestamp = datetime.now(timezone.utc)
+    station = SimpleNamespace(
+        id=uuid4(),
+        name="Test Station",
+        location=None,
+        created_at=timestamp,
+        updated_at=timestamp,
+    )
+    track = SimpleNamespace(
+        id=uuid4(),
+        start_station_id=station.id,
+        end_station_id=station.id,
+        length_meters=1234.5,
+        max_speed_kph=160,
+        created_at=timestamp,
+        updated_at=timestamp,
+    )
+    train = SimpleNamespace(
+        id=uuid4(),
+        designation="Test Express",
+        capacity=200,
+        max_speed_kph=220,
+        created_at=timestamp,
+        updated_at=timestamp,
+    )
+    return {"station": station, "track": track, "train": train}
+
+
+def test_network_snapshot_prefers_repository_data(monkeypatch: pytest.MonkeyPatch, sample_entities: dict[str, SimpleNamespace]) -> None:
+    station = sample_entities["station"]
+    track = sample_entities["track"]
+    train = sample_entities["train"]
+
+    monkeypatch.setattr(StationRepository, "list_active", lambda self: [station])
+    monkeypatch.setattr(TrackRepository, "list_all", lambda self: [track])
+    monkeypatch.setattr(TrainRepository, "list_all", lambda self: [train])
+
+    snapshot = get_network_snapshot(session=None)  # type: ignore[arg-type]
+
+    assert snapshot["stations"]
+    assert snapshot["stations"][0]["name"] == station.name
+    assert snapshot["tracks"][0]["lengthMeters"] == pytest.approx(track.length_meters)
+    assert snapshot["trains"][0]["designation"] == train.designation
+    assert snapshot["trains"][0]["operatingTrackIds"] == []
+
+
+def test_network_snapshot_falls_back_when_repositories_empty(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(StationRepository, "list_active", lambda self: [])
+    monkeypatch.setattr(TrackRepository, "list_all", lambda self: [])
+    monkeypatch.setattr(TrainRepository, "list_all", lambda self: [])
+
+    snapshot = get_network_snapshot(session=None)  # type: ignore[arg-type]
+
+    assert snapshot["stations"]
+    assert snapshot["trains"]
+    assert any(station["name"] == "Central" for station in snapshot["stations"])