feat: add tests for import polling, login page, money utilities, and query keys

- Implemented tests for import polling functionality, ensuring correct behavior for active and terminal import statuses.
- Created tests for the login page, validating user interactions and error handling.
- Added unit tests for money utility functions, covering parsing, formatting, and summation of monetary values.
- Developed tests for query keys, ensuring proper scoping and invalidation roots.

chore: setup testing environment and configuration

- Added setup file for testing with Vitest and Testing Library.
- Configured TypeScript and Vite for the frontend project.
- Created Docker and Nginx configurations for local development and production environments.
- Established a PostgreSQL initialization script for setting up application roles.

docs: add README and environment configuration for infra

- Included README for the infra directory, detailing local development setup and service descriptions.
- Created an example environment configuration file for local development with placeholders for sensitive information.

backend/tests/test_postgres_and_s3.py

@@ -0,0 +1,52 @@
+import os
+import uuid
+from datetime import date
+
+import pytest
+from sqlalchemy import create_engine
+from sqlalchemy.exc import DBAPIError
+from sqlalchemy.orm import Session
+
+from app.db.session import set_space_context
+from app.imports.blob import get_blob_store
+from app.ledger.models import Account
+from app.spaces.models import FinancialSpace
+
+
+@pytest.mark.skipif(not os.getenv("RLS_DATABASE_URL"), reason="requires restricted PostgreSQL role")
+def test_postgres_rls_requires_matching_transaction_context() -> None:
+    engine = create_engine(os.environ["RLS_DATABASE_URL"])
+    with Session(engine) as db:
+        space = FinancialSpace(name="RLS integration")
+        db.add(space)
+        db.commit()
+        space_id = space.id
+
+        db.add(Account(space_id=space_id, name="Blocked", kind="cash", opened_on=date.today()))
+        with pytest.raises(DBAPIError):
+            db.commit()
+        db.rollback()
+
+        set_space_context(db, space_id)
+        db.add(Account(space_id=space_id, name="Allowed", kind="cash", opened_on=date.today()))
+        db.commit()
+
+        set_space_context(db, uuid.uuid4())
+        assert db.query(Account).count() == 0
+        db.rollback()
+        set_space_context(db, space_id)
+        persisted_space = db.get(FinancialSpace, space_id)
+        assert persisted_space is not None
+        db.delete(persisted_space)
+        db.commit()
+    engine.dispose()
+
+
+@pytest.mark.skipif(not os.getenv("S3_ENDPOINT_URL"), reason="requires S3-compatible storage")
+def test_s3_blob_round_trip() -> None:
+    store = get_blob_store()
+    key = uuid.uuid4().hex
+    payload = b"synthetic statement payload"
+    store.put(key, payload)
+    assert store.get(key) == payload
+    store.delete(key)