fix(trade-dashboard): fix import errors and alembic migration

- database.py: remove dead pre-definition of DATABASE_URL with
  undefined db_user/db_pass variables
- models.py: add missing Table import from sqlalchemy
- alembic/env.py: replace deprecated run_async() with asyncio.run()
  (removed in SQLAlchemy 2.0)
- alembic 001_initial: use raw SQL for CREATE TYPE instead of
  op.create_enum() which requires alembic_postgresql_enum

Migration 001_initial successfully applied to trading_data DB.

apps/base/customer1/trade-dashboard/alembic/env.py

@@ -54,8 +54,9 @@ async def run_migrations_online() -> None:
     await connectable.dispose()
 
 
+import asyncio
+
 if context.is_offline_mode():
     run_migrations_offline()
 else:
-    from sqlalchemy.ext.asyncio import run_async  # noqa: E402
-    run_async(run_migrations_online())
+    asyncio.run(run_migrations_online())

apps/base/customer1/trade-dashboard/alembic/versions/001_initial.py

@@ -15,7 +15,7 @@ depends_on = None
 
 
 def upgrade() -> None:
-    op.create_enum("position_direction", "long", "short", schema="public", create_type=True)
+    op.execute('CREATE TYPE position_direction AS ENUM (\'long\', \'short\')')
 
     op.create_table(
         "positions",

apps/base/customer1/trade-dashboard/app/database.py

@@ -1,17 +1,8 @@
-from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
-from sqlalchemy import MetaData
-
-# Connection to hermes-pgdb CNPG cluster
-DATABASE_URL = (
-    f"postgresql+asyncpg://{db_user}:{db_pass}"
-    f"@hermes-pgdb-rw.customer1.svc.cluster.local:5432/trading_data"
-).format(
-    db_user="trading",
-    db_pass="TRADING_DB_PASSWORD",  # overridden by env
-)
-
 import os
 
+from sqlalchemy import MetaData
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
 DB_USER = os.getenv("DB_USER", "trading")
 DB_PASS = os.getenv("DB_PASSWORD", "")
 DB_HOST = os.getenv("DB_HOST", "hermes-pgdb-rw.customer1.svc.cluster.local")

apps/base/customer1/trade-dashboard/app/models.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Column, String, Numeric, Enum, DateTime, JSON, func
+from sqlalchemy import Column, String, Numeric, Enum, DateTime, JSON, func, Table
 from sqlalchemy.dialects.postgresql import UUID
 import uuid