Initial commit: ImpactFlow Discovery + Google OAuth auth layer

Discovery service (pre-existing): FastAPI + async SQLAlchemy + Alembic +
SQLite + Anthropic, with a five-prompt static UI that produces an Enneagram
+ Ikigai profile.

Auth implementation (this change set) follows
Impact_Flow_Auth_Plan_OAuth.html, adapted to the discovery_conversation /
discovery_profile schema:

- app/auth.py: Google OAuth registration, JWT issue/decode, dual-auth
  dependency (Bearer JWT or X-API-Key), refresh-token hashing, domain
  allow-list, synthetic api-key-admin user
- app/tracking.py: ActivityTrackingMiddleware + log_activity helper;
  tags machine-to-machine calls source=mcp
- app/routers/auth.py: /api/auth/{login,callback,refresh,logout},
  /api/me, /api/me/{stats,sessions,sessions/{id}}
- app/routers/activity.py: /api/activity, /api/activity/summary,
  /api/admin/activity, plus prune_old_activity (90-day retention)
- app/routers/discovery.py: every route now user-scoped via the auth
  dependency; /discovery/profile/{user_id} -> /discovery/profile/me
- alembic/versions/002_add_auth.py: users, refresh_tokens, activity_log
- tests/test_auth.py: 8 tests covering 401 paths, X-API-Key admin
  resolution, JWT round-trip, admin gating, domain allow-list
- README.md: Authentication section, expanded env-var table, updated
  data-model and API-reference tables
- .env.example: new GOOGLE_*, JWT_*, IMPACTFLOW_API_KEY, CORS_*,
  ALLOWED_EMAIL_DOMAINS placeholders
- .gitignore: also exclude data/*.log

Tests: 19/19 pass (11 pre-existing + 8 new). smoke_test.py exercises the
full discovery flow under X-API-Key plus 401 paths, OAuth login redirect,
activity logging, and /api/me/stats.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/database.py

@@ -0,0 +1,53 @@
+"""Async SQLAlchemy engine, session factory, and declarative base.
+
+The SQLite database file lives under ./data so it can be persisted via a
+Docker volume mount. The data directory is created on import if missing.
+"""
+import os
+
+from dotenv import load_dotenv
+from sqlalchemy.ext.asyncio import (
+    AsyncSession,
+    async_sessionmaker,
+    create_async_engine,
+)
+from sqlalchemy.orm import DeclarativeBase
+
+load_dotenv()
+
+DATABASE_URL = os.getenv(
+    "DATABASE_URL", "sqlite+aiosqlite:///./data/discovery.db"
+)
+
+
+def _ensure_sqlite_dir(url: str) -> None:
+    """Make sure the directory holding the SQLite file exists."""
+    if "sqlite" not in url:
+        return
+    # everything after the scheme's :/// is the filesystem path
+    if ":///" not in url:
+        return
+    path = url.split(":///", 1)[1]
+    directory = os.path.dirname(path)
+    if directory:
+        os.makedirs(directory, exist_ok=True)
+
+
+_ensure_sqlite_dir(DATABASE_URL)
+
+
+class Base(DeclarativeBase):
+    """Declarative base shared by all ORM models."""
+
+
+engine = create_async_engine(DATABASE_URL, echo=False, future=True)
+
+AsyncSessionLocal = async_sessionmaker(
+    engine, class_=AsyncSession, expire_on_commit=False
+)
+
+
+async def get_db() -> AsyncSession:
+    """FastAPI dependency that yields a scoped async session."""
+    async with AsyncSessionLocal() as session:
+        yield session