Health monitoring:
- gitserver: /health endpoint on port 8021 (DB + Redis ping)
- git-hook: hyper health server on port 8083 with /health
- email-worker: hyper health server on port 8084 with /health
- K8s probes updated to httpGet for all three services
Metrics (via /metrics endpoint):
- git-hook: hook_tasks_total/success/failed/locked/retried/exhausted,
hook_sync_branches/tags_changed_total
- email: email_queued/consumed/sent/failed_total,
email_validation_skipped/build_errors/send_attempts_total
- Remove all use slog::* imports and log: slog::Logger fields
- ssh/handle.rs: replace slog macro chains with tracing::{info!, warn!,
error!, debug!}; remove log field from GitSshHandle
- ssh/authz.rs, ssh/mod.rs, ssh/server.rs: remove slog Logger fields
- http/: auth.rs, handler.rs, mod.rs, routes.rs: remove slog usage
- hook/: pool worker, sync modules, webhook_dispatch.rs: remove slog
- Downgrade russh from 0.55.0 to 0.50.4
- Remove unused flate2 feature from russh dependency
- Use info!(logger, "{}", format!(...)) for channel lifecycle log messages
