feat(mdd): add Ops Mode — deployment runbooks with canary-gated multi-region execution

Adds three new MDD commands for deployment documentation and execution:
- /mdd ops <description>  — create a runbook in .mdd/ops/ (services, regions, images, credentials, webhooks)
- /mdd runop <slug>       — execute runbook: pre-flight health check → canary-gated region deploy → post-flight verify
- /mdd update-op <slug>   — edit an existing runbook with diff preview

Key features:
- Per-region Docker image name overrides (different image names for EU vs US)
- Deployment strategy config: sequential/parallel, health_check/manual/none gate, stop/skip_region/rollback on failure
- Service health status tracked per-region in frontmatter, updated on every runop
- Canary pattern: deploy to lower deploy_order region first, gate on health, then primary
- .mdd/ops/ bootstrapped silently on every /mdd invocation alongside docs/ and audits/
- Status, Scan, Graph, Audit, Commands modes all updated to include ops runbooks
- Prominent Ops Mode section added to README.md and docs/index.html

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

Author: timclausendev-web