fix: guard test cleanup to a dedicated lyra_test DB (never wipe live data)

Test suites were running DELETE FROM.../deleteMany() against whatever
DATABASE_URL pointed to, which was the live app database, wiping user
credentials and library. Add a guard in both the worker conftest and
web test setup that raises before any cleanup unless the target DB
name ends in '_test'. Default DATABASE_URL to lyra_test when unset in
the worker, and make `npm test` target lyra_test explicitly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/tests/conftest.py

@@ -1,12 +1,24 @@
 import os
 
+os.environ.setdefault("DATABASE_URL", "postgresql://lyra:lyra@localhost:5432/lyra_test")
+
 import psycopg
 import pytest
 
 
+def _require_test_db(dsn: str) -> None:
+    name = dsn.rsplit("/", 1)[-1].split("?")[0]
+    if not name.endswith("_test"):
+        raise RuntimeError(
+            f"refusing to run destructive test fixtures against non-test database '{name}'. "
+            "Point DATABASE_URL at a database whose name ends in '_test' (e.g. lyra_test)."
+        )
+
+
 @pytest.fixture()
 def conn():
     dsn = os.environ["DATABASE_URL"]
+    _require_test_db(dsn)
     connection = psycopg.connect(dsn)
     # Clean up any pre-existing rows before the test runs (Job cascades from Request).
     with connection.cursor() as cur: