fix(tests): repair test_profile_duplicate_names so the suite can run

The file still used the pre-refactor flat imports and a sys.path hack:

    sys.path.insert(0, str(Path(__file__).parent.parent))
    from database import Base, VoiceProfile as DBVoiceProfile
    from profiles import create_profile, update_profile

`profiles` now lives at backend/services/profiles.py, so collection raised
ImportError. Because pytest aborts the whole run on a collection error, this
one file meant `just test` ran zero tests — duplicate-name validation has had
no coverage since the services refactor.

Switch to package imports like every other test module, and drop
DBVoiceProfile, which was imported but never used.

That exposed a second, latent bug: all 6 tests passed but every one errored in
teardown with PermissionError WinError 32. The fixture closed the session and
then rmtree'd the temp dir, but closing a session does not release
SQLAlchemy's pooled connection, so SQLite still held test.db open on Windows.
Dispose the engine before removing the directory.

6 passed, and full-suite collection goes from aborting to 170 tests.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

backend/tests/test_profile_duplicate_names.py

@@ -12,7 +12,7 @@ from pathlib import Path
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 
-from backend.database import Base, VoiceProfile as DBVoiceProfile
+from backend.database import Base
 from backend.models import VoiceProfileCreate
 from backend.services.profiles import create_profile, update_profile
 
@@ -33,8 +33,11 @@ def test_db():
 
     yield db
 
-    # Cleanup
+    # Cleanup. The engine must be disposed as well as the session closed —
+    # on Windows the pooled connection keeps the .db file open and rmtree
+    # fails with WinError 32.
     db.close()
+    engine.dispose()
     shutil.rmtree(temp_dir)