feat(01-05): final cutover — delete data/, prune config.py, async-only tests

- Delete backend/data/ tracked files (D-04): flat-file metadata, settings.json,
  topics.json, and uploaded files removed from git; backend/data/ added to
  .gitignore (empty dir remains on macOS due to ACL — no tracked files remain)
- Prune backend/config.py: remove DATA_DIR, UPLOADS_DIR, METADATA_DIR,
  TOPICS_FILE, ensure_data_dirs(); rebase SETTINGS_FILE as derived path from
  settings.data_dir (Phase 1 flat-file settings kept per plan decision)
- Prune backend/tests/conftest.py: remove isolated_data_dir autouse fixture
  and sync TestClient client fixture; add SQLite type compatibility shim
  (visit_INET/JSONB) so in-memory db_session can create tables with
  PostgreSQL-specific column types; add live_services_available fixture
- Rewrite backend/tests/test_documents.py: delete all legacy sync tests,
  remove all @pytest.mark.xfail markers; async-only document tests now
  use async_client + storage service directly for topic wiring
- Rewrite backend/tests/test_health.py: delete legacy sync test_health(client);
  remove @pytest.mark.xfail from test_health_checks_postgres_and_minio
- Port backend/tests/test_topics.py to async_client (sync client removed)
- Port backend/tests/test_settings.py to async_client with monkeypatch for
  SETTINGS_FILE isolation (settings remain flat-file in Phase 1)

backend/tests/test_topics.py

@@ -1,11 +1,23 @@
-def test_list_topics_empty(client):
-    resp = client.get("/api/topics")
+"""
+Topics API tests — async only (Plan 05 cutover).
+
+Legacy sync tests (using the flat-file storage layer and sync TestClient) were
+updated to async in Plan 05 to match the new session-injected API routes.
+"""
+from __future__ import annotations
+
+
+async def test_list_topics_empty(async_client):
+    resp = await async_client.get("/api/topics")
     assert resp.status_code == 200
     assert resp.json()["topics"] == []
 
 
-def test_create_topic(client):
-    resp = client.post("/api/topics", json={"name": "Finance", "description": "Financial docs", "color": "#ff0000"})
+async def test_create_topic(async_client):
+    resp = await async_client.post(
+        "/api/topics",
+        json={"name": "Finance", "description": "Financial docs", "color": "#ff0000"},
+    )
     assert resp.status_code == 200
     data = resp.json()
     assert data["name"] == "Finance"
@@ -13,60 +25,66 @@ def test_create_topic(client):
     assert "id" in data
 
 
-def test_create_topic_deduplication(client):
-    client.post("/api/topics", json={"name": "Finance"})
-    resp = client.post("/api/topics", json={"name": "finance"})  # case-insensitive
+async def test_create_topic_deduplication(async_client):
+    await async_client.post("/api/topics", json={"name": "Finance"})
+    resp = await async_client.post("/api/topics", json={"name": "finance"})  # case-insensitive
     assert resp.status_code == 200
-    topics = client.get("/api/topics").json()["topics"]
+    topics = (await async_client.get("/api/topics")).json()["topics"]
     assert len(topics) == 1
 
 
-def test_update_topic(client):
-    create = client.post("/api/topics", json={"name": "Old Name"}).json()
-    resp = client.patch(f"/api/topics/{create['id']}", json={"name": "New Name"})
+async def test_update_topic(async_client):
+    create = (await async_client.post("/api/topics", json={"name": "Old Name"})).json()
+    resp = await async_client.patch(f"/api/topics/{create['id']}", json={"name": "New Name"})
     assert resp.status_code == 200
     assert resp.json()["name"] == "New Name"
 
 
-def test_update_topic_not_found(client):
-    resp = client.patch("/api/topics/nonexistent", json={"name": "X"})
+async def test_update_topic_not_found(async_client):
+    resp = await async_client.patch(
+        "/api/topics/00000000-0000-0000-0000-000000000000",
+        json={"name": "X"},
+    )
     assert resp.status_code == 404
 
 
-def test_delete_topic(client):
-    create = client.post("/api/topics", json={"name": "ToDelete"}).json()
-    resp = client.delete(f"/api/topics/{create['id']}")
+async def test_delete_topic(async_client):
+    create = (await async_client.post("/api/topics", json={"name": "ToDelete"})).json()
+    resp = await async_client.delete(f"/api/topics/{create['id']}")
     assert resp.status_code == 200
     assert resp.json()["success"] is True
 
-    topics = client.get("/api/topics").json()["topics"]
+    topics = (await async_client.get("/api/topics")).json()["topics"]
     assert not any(t["name"] == "ToDelete" for t in topics)
 
 
-def test_delete_topic_cascades_to_documents(client, sample_txt):
+async def test_delete_topic_cascades_to_documents(async_client, db_session, sample_txt):
     # Create a topic
-    topic = client.post("/api/topics", json={"name": "Legal"}).json()
+    topic = (await async_client.post("/api/topics", json={"name": "Legal"})).json()
 
-    # Upload doc (no auto classify to control topics manually)
+    # Upload doc (no auto classify)
     with open(sample_txt, "rb") as f:
-        upload = client.post(
-            "/api/documents/upload",
-            files={"file": ("sample.txt", f, "text/plain")},
-            data={"auto_classify": "false"},
+        upload = (
+            await async_client.post(
+                "/api/documents/upload",
+                files={"file": ("sample.txt", f, "text/plain")},
+                data={"auto_classify": "false"},
+            )
         ).json()
 
-    # Manually set topic on the document via classify endpoint
-    import services.storage as st
-    st.update_document_topics(upload["id"], ["Legal"])
+    # Manually set topic via the storage service
+    from services import storage
+
+    await storage.update_document_topics(db_session, upload["id"], ["Legal"])
 
     # Delete topic
-    client.delete(f"/api/topics/{topic['id']}")
+    await async_client.delete(f"/api/topics/{topic['id']}")
 
     # Verify document no longer has the topic
-    doc = client.get(f"/api/documents/{upload['id']}").json()
+    doc = (await async_client.get(f"/api/documents/{upload['id']}")).json()
     assert "Legal" not in doc["topics"]
 
 
-def test_delete_topic_not_found(client):
-    resp = client.delete("/api/topics/nonexistent")
+async def test_delete_topic_not_found(async_client):
+    resp = await async_client.delete("/api/topics/nonexistent")
     assert resp.status_code == 404