fix: setup routing, async bcrypt, password hashing, clean command

- Add SetupGuard component: redirects to /setup if setup not complete,
  shown as spinner while loading. All routes except /setup now wrapped.
- SetupPage redirects to /login on mount when setup already done.
- Fix async blocking: offload bcrypt.hashpw and bcrypt.checkpw to
  run_in_executor so they never stall the asyncio event loop.
- Hash password with SHA-256 (SubtleCrypto) before transmission; added
  src/utils/crypto.ts with sha256Hex(). Backend stores bcrypt(sha256).
- Add Makefile with make up/down/restart/logs/clean targets.
- Add tests: _check_password async, concurrent bcrypt, expired session,
  login-without-setup, run_setup event-loop interleaving.
- Update Architekture.md and Features.md to reflect all changes.

backend/tests/test_services/test_auth_service.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+import asyncio
+import inspect
 from pathlib import Path
 
 import aiosqlite
@@ -30,6 +32,50 @@ async def db(tmp_path: Path) -> aiosqlite.Connection:  # type: ignore[misc]
     await conn.close()
 
 
+@pytest.fixture
+async def db_no_setup(tmp_path: Path) -> aiosqlite.Connection:  # type: ignore[misc]
+    """Provide an initialised DB with no setup performed."""
+    conn: aiosqlite.Connection = await aiosqlite.connect(str(tmp_path / "auth_nosetup.db"))
+    conn.row_factory = aiosqlite.Row
+    await init_db(conn)
+    yield conn
+    await conn.close()
+
+
+class TestCheckPasswordAsync:
+    async def test_check_password_is_coroutine_function(self) -> None:
+        """_check_password must be a coroutine function (runs in thread executor)."""
+        assert inspect.iscoroutinefunction(auth_service._check_password)  # noqa: SLF001
+
+    async def test_check_password_returns_true_on_match(self) -> None:
+        """_check_password returns True for a matching plain/hash pair."""
+        import bcrypt
+
+        hashed = bcrypt.hashpw(b"secret", bcrypt.gensalt()).decode()
+        result = await auth_service._check_password("secret", hashed)  # noqa: SLF001
+        assert result is True
+
+    async def test_check_password_returns_false_on_mismatch(self) -> None:
+        """_check_password returns False when the password does not match."""
+        import bcrypt
+
+        hashed = bcrypt.hashpw(b"secret", bcrypt.gensalt()).decode()
+        result = await auth_service._check_password("wrong", hashed)  # noqa: SLF001
+        assert result is False
+
+    async def test_check_password_does_not_block_event_loop(self) -> None:
+        """_check_password awaits without blocking; event-loop tasks can interleave."""
+        import bcrypt
+
+        hashed = bcrypt.hashpw(b"secret", bcrypt.gensalt()).decode()
+        # Running two concurrent checks must complete without deadlock.
+        results = await asyncio.gather(
+            auth_service._check_password("secret", hashed),  # noqa: SLF001
+            auth_service._check_password("wrong", hashed),  # noqa: SLF001
+        )
+        assert results == [True, False]
+
+
 class TestLogin:
     async def test_login_returns_session_on_correct_password(
         self, db: aiosqlite.Connection
@@ -47,6 +93,13 @@ class TestLogin:
         with pytest.raises(ValueError, match="Incorrect password"):
             await auth_service.login(db, password="wrongpassword", session_duration_minutes=60)
 
+    async def test_login_raises_when_no_hash_configured(
+        self, db_no_setup: aiosqlite.Connection
+    ) -> None:
+        """login() raises ValueError when setup has not been run."""
+        with pytest.raises(ValueError, match="No password is configured"):
+            await auth_service.login(db_no_setup, password="any", session_duration_minutes=60)
+
     async def test_login_persists_session(self, db: aiosqlite.Connection) -> None:
         """login() stores the session in the database."""
         from app.repositories import session_repo
@@ -73,6 +126,27 @@ class TestValidateSession:
         with pytest.raises(ValueError, match="not found"):
             await auth_service.validate_session(db, "deadbeef" * 8)
 
+    async def test_validate_raises_for_expired_session(
+        self, db: aiosqlite.Connection
+    ) -> None:
+        """validate_session() raises ValueError and removes an expired session."""
+        from app.repositories import session_repo
+
+        # Create a session that expired in the past.
+        past_token = "expiredtoken01" * 4  # 56 chars, unique enough for tests
+        await session_repo.create_session(
+            db,
+            token=past_token,
+            created_at="2000-01-01T00:00:00+00:00",
+            expires_at="2000-01-01T01:00:00+00:00",
+        )
+
+        with pytest.raises(ValueError, match="expired"):
+            await auth_service.validate_session(db, past_token)
+
+        # The expired session must have been deleted.
+        assert await session_repo.get_session(db, past_token) is None
+
 
 class TestLogout:
     async def test_logout_removes_session(self, db: aiosqlite.Connection) -> None: