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>

.env.example

@@ -0,0 +1,29 @@
+ANTHROPIC_API_KEY=your_anthropic_api_key_here
+DATABASE_URL=sqlite+aiosqlite:///./data/discovery.db
+HOST_BIND_IP=0.0.0.0
+HOST_PORT=8011
+
+# Optional: override the Anthropic model used for extraction
+ANTHROPIC_MODEL=claude-sonnet-4-5
+
+# Google OAuth (web client type). Register the redirect URI below as an
+# authorized redirect URI in the Google Cloud Console for this client.
+GOOGLE_CLIENT_ID=xxxx.apps.googleusercontent.com
+GOOGLE_CLIENT_SECRET=GOCSPX-xxxx
+OAUTH_REDIRECT_URI=http://localhost:8000/api/auth/callback
+
+# Random 64-char URL-safe strings. Generate with:
+#   python -c "import secrets; print(secrets.token_urlsafe(48))"
+JWT_SECRET=generate-a-random-64-char-string
+IMPACTFLOW_API_KEY=generate-another-random-64-char-string
+
+# JWT lifetimes (minutes / days).
+JWT_ACCESS_MINUTES=15
+JWT_REFRESH_DAYS=7
+
+# Comma-separated allow-list of browser origins for CORS.
+CORS_ALLOWED_ORIGINS=http://localhost:8000,http://100.103.206.4:8000
+
+# Optional comma-separated email-domain allow-list (e.g. "computerim.com").
+# Empty means any verified Google email is accepted.
+ALLOWED_EMAIL_DOMAINS=