T10: Monitoring, Performance, Documentation & Environment Config — 38 tests, ruff clean, docs OK

- Extended health endpoint: DB+Redis+Storage+Worker checks with degraded status
- Prometheus metrics endpoint: admin-only, text/plain format
- Metrics: http_requests_total, db_pool_connections, arq_jobs_total
- Structured JSON logging (structlog): timestamp, level, method, path, status, duration_ms, tenant_id
- Performance: page_size max 100 enforced (422), streaming CSV export (StreamingResponse)
- Scripts: seed_perf_data.py, check_indexes.py
- Docs: admin-guide.md (Deploy, Backup, Restore, Env-Vars, Troubleshooting), api-overview.md
- README updated: prod setup, API section, env profiles, admin-guide link
- .env.example: added SECRET_KEY, STORAGE_PATH, SMTP_* vars
- 38 new tests, full regression 564/564 pass (0 failures)
- Ruff: all checks passed

.env.example

@@ -31,6 +31,20 @@ PASSWORD_RESET_EXPIRY_HOURS=1
 # CORS allowed origins (comma-separated, NO wildcards)
 CORS_ORIGINS=http://localhost:5173,http://localhost:3000
 
+# Secret Key (for signing, sessions — use a secure random string ≥32 chars in prod)
+SECRET_KEY=change-me-in-production-use-a-secure-random-string
+
+# Storage (file uploads, DMS)
+STORAGE_PATH=/tmp
+
+# SMTP / Email
+SMTP_HOST=localhost
+SMTP_PORT=587
+SMTP_USERNAME=
+SMTP_PASSWORD=
+SMTP_FROM_EMAIL=noreply@leocrm.local
+SMTP_USE_TLS=true
+
 # Rate limiting
 RATE_LIMIT_LOGIN_MAX=5
 RATE_LIMIT_LOGIN_WINDOW=900