Enhance production test suite: FX coverage, Alpaca equity, Redis memory, journalctl

- audit_data.py: Add circuit_breaker_events table check, FX pair coverage
- test_e2e.py: Add ensemble weight sum validation, Alpaca account equity check
- test_infra.py: Add Redis memory/key count, journalctl error scan, 80% disk threshold
- MAINTENANCE.md: Expand daily checklist, add weekly items (strategy weights,
  Alpaca equity, optimization review), enhance emergency procedures (Alpaca 403,
  NaN models, disk full), add key paths and monitoring URLs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: axumweyane