Add unit tests for station service and enhance documentation

- Introduced unit tests for the station service, covering creation, updating, and archiving of stations.
- Added detailed building block view documentation outlining the architecture of the Rail Game system.
- Created runtime view documentation illustrating key user interactions and system behavior.
- Developed concepts documentation detailing domain models, architectural patterns, and security considerations.
- Updated architecture documentation to reference new detailed sections for building block and runtime views.

backend/scripts/stations_load.py

@@ -0,0 +1,86 @@
+from __future__ import annotations
+
+"""CLI for loading normalized station JSON into the database."""
+
+import argparse
+import json
+import sys
+from pathlib import Path
+from typing import Any, Iterable, Mapping
+
+from backend.app.db.session import SessionLocal
+from backend.app.models import StationCreate
+from backend.app.repositories import StationRepository
+
+
+def build_argument_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        description="Load normalized station data into PostGIS"
+    )
+    parser.add_argument(
+        "input",
+        type=Path,
+        help="Path to the normalized station JSON file produced by stations_import.py",
+    )
+    parser.add_argument(
+        "--commit/--no-commit",
+        dest="commit",
+        default=True,
+        help="Commit the transaction (default: commit). Use --no-commit for dry runs.",
+    )
+    return parser
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = build_argument_parser()
+    args = parser.parse_args(argv)
+
+    if not args.input.exists():
+        parser.error(f"Input file {args.input} does not exist")
+
+    with args.input.open("r", encoding="utf-8") as handle:
+        payload = json.load(handle)
+
+    stations_data = payload.get("stations") or []
+    if not isinstance(stations_data, list):
+        parser.error("Invalid payload: 'stations' must be a list")
+
+    try:
+        station_creates = _parse_station_entries(stations_data)
+    except ValueError as exc:
+        parser.error(str(exc))
+
+    created = load_stations(station_creates, commit=args.commit)
+
+    print(f"Loaded {created} stations from {args.input}")
+    return 0
+
+
+def _parse_station_entries(entries: Iterable[Mapping[str, Any]]) -> list[StationCreate]:
+    parsed: list[StationCreate] = []
+    for entry in entries:
+        try:
+            parsed.append(StationCreate(**entry))
+        except Exception as exc:  # pragma: no cover - validated in tests
+            raise ValueError(f"Invalid station entry {entry}: {exc}") from exc
+    return parsed
+
+
+def load_stations(stations: Iterable[StationCreate], commit: bool = True) -> int:
+    created = 0
+    with SessionLocal() as session:
+        repo = StationRepository(session)
+
+        for create_schema in stations:
+            repo.create(create_schema)
+            created += 1
+
+        if commit:
+            session.commit()
+        else:
+            session.rollback()
+    return created
+
+
+if __name__ == "__main__":
+    sys.exit(main())