docs: fill remaining feature gaps (deploying, alerts, gpu, nomad tokens)

[pipozzz]

Follow-up to #1 — closes the gaps found when auditing the docs against the full nomploy feature set.

New Core pages, wired into the sidebar:

• Deploying (Services) — the three Compose deploy styles: Compose→Nomad HCL translation, native HCL deployed verbatim, and Nomad Pack; health-gated auto_revert rollouts.
• Monitoring & Alerts (Advanced) — metric alert rules (LB, per-service, and the cluster security/observability health metrics crowdsec_* / otel_collector_up / log_agent_up), debounce, and silences. (Previously only the 4 health metrics were mentioned inside Security.)
• GPU workloads (Advanced) — enable GPU support on a node, then request a GPU in Compose or native HCL.
• Nomad ACL tokens (Server) — mint/list/revoke scoped tokens from Settings for direct Nomad API/CLI/Terraform access.

Ported from the main repo's docs/ where applicable (gpu, deploying, alerts) and expanded. No app/runtime code changed.

Note: the repo's lint-and-typecheck PR check fails on pre-existing, repo-wide formatting debt unrelated to these docs (same as #1).