Let people name accounts and use the names to tell accounts apart

Connections get an account_name (migration 0039) that the owner sets with
PATCH /api/connections/<id>; the account label stays the account's
identity, so signing in again still finds it. When someone has more than
one account of a service, its tools are listed as "Telegram · <account>"
and the model sees each account's actions under the account's name
(telegram_send_message_alerts_bot) with the account in the description,
instead of _1 and _2. Actions shared by different services are named
after the service. Tools a user renamed keep their name.

tests/storage/db/test_migration_0039.py

@@ -0,0 +1,50 @@
+"""Migration round-trip test for 0039_connection_account_name."""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+from sqlalchemy import text
+
+
+pytestmark = pytest.mark.integration
+
+_0039 = "0039_connection_account_name"
+_0038 = "0038_connections"
+
+
+def _run_alembic(url: str, *args: str) -> None:
+    ini = Path(__file__).resolve().parents[3] / "docsgpt" / "alembic.ini"
+    subprocess.check_call(
+        [sys.executable, "-m", "alembic", "-c", str(ini), *args],
+        timeout=120,
+        env={**os.environ, "POSTGRES_URI": url},
+    )
+
+
+def _has_column(conn) -> bool:
+    return conn.execute(
+        text(
+            "SELECT 1 FROM information_schema.columns WHERE table_schema = 'public' "
+            "AND table_name = 'connector_sessions' AND column_name = 'account_name'"
+        )
+    ).fetchone() is not None
+
+
+class TestMigration0039RoundTrip:
+    def test_head_has_account_name(self, pg_engine):
+        with pg_engine.connect() as conn:
+            assert _has_column(conn)
+
+    def test_downgrade_drops_then_upgrade_restores(self, pg_engine):
+        url = pg_engine.url.render_as_string(hide_password=False)
+        _run_alembic(url, "downgrade", _0038)
+        with pg_engine.connect() as conn:
+            assert not _has_column(conn)
+        _run_alembic(url, "upgrade", "head")
+        with pg_engine.connect() as conn:
+            assert _has_column(conn)