Initial commit: CI Agent competitive-intelligence monitoring app

FastAPI + Celery + Next.js + Postgres/Redis app with company monitoring,
source collection, LLM-based change analysis, enrichment, and account
security (Turnstile, escalating lockout, email verification).

apps/api/app/db/session.py

@@ -0,0 +1,50 @@
+"""Async SQLAlchemy engine/session setup.
+
+Works against Postgres (`postgresql+psycopg://...`) or SQLite
+(`sqlite+aiosqlite://...`) depending on `DATABASE_URL` - the same models and
+repositories run against either, which is what makes the no-Docker local dev
+path possible.
+"""
+
+from __future__ import annotations
+
+from collections.abc import AsyncGenerator
+from functools import lru_cache
+
+from sqlalchemy.ext.asyncio import (
+    AsyncEngine,
+    AsyncSession,
+    async_sessionmaker,
+    create_async_engine,
+)
+
+from app.core.config import get_settings
+
+
+@lru_cache
+def get_engine() -> AsyncEngine:
+    settings = get_settings()
+    connect_args = {}
+    if settings.database_url.startswith("sqlite"):
+        connect_args = {"check_same_thread": False}
+    return create_async_engine(
+        settings.database_url,
+        echo=False,
+        pool_pre_ping=True,
+        connect_args=connect_args,
+    )
+
+
+@lru_cache
+def get_sessionmaker() -> async_sessionmaker[AsyncSession]:
+    return async_sessionmaker(bind=get_engine(), expire_on_commit=False)
+
+
+async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    session_factory = get_sessionmaker()
+    async with session_factory() as session:
+        try:
+            yield session
+        except Exception:
+            await session.rollback()
+            raise