Get Started: install nic and deploy your first NKP cluster

Part of epic #621.

Goal

Replace the Classic "Get Started" flow with an NKP-first path that takes a new user from zero to a running cluster, using Hetzner as the default provider (cheapest, easiest, EU data residency).

Scope

Rewrite / replace docs/docs/get-started/:

• Install nic — binary install (release downloads, platform notes), version check, shell completion
• Quickstart — end-to-end Hetzner deployment as the happy path: config file, credentials/env, nic validate, nic deploy, access the landing page, nic destroy
• Cloud provider overview — at-a-glance table: AWS ✅ full, Hetzner ✅ full (recommended starter), GCP / Azure / Local 🚧 planned. Short "why Hetzner first?" callout.
• Deploy walkthrough — longer guided version of the quickstart, explaining each step, what Terraform state is being created, what the operator does after the cluster is up, how to verify health

Out of scope

• Per-provider deep-dive how-tos (separate sub-issue)
• Pack installation (separate sub-issue)
• CLI command reference (separate sub-issue)

Acceptance criteria

• A new user can reach a working Hetzner cluster by following quickstart only
• Classic's get-started/ is preserved under /classic/get-started/
• Provider support matrix is accurate and links to each provider's how-to
• Walkthrough explains what happens (not just which commands to run)

Reference

Repos:

• nic CLI: https://github.com/nebari-dev/nebari-infrastructure-core
• Nebari Operator: https://github.com/nebari-dev/nebari-operator

Source in nebari-infrastructure-core:

• Hetzner design + implementation: docs/plans/2026-02-27-hetzner-provider-design.md and -implementation.md
• Example configs: examples/

Notes for dev rel decomposition

Likely sub-tasks: (a) install page, (b) Hetzner quickstart, (c) provider matrix, (d) full deploy walkthrough, (e) test flow end-to-end with a real Hetzner account.

Start with docs/docs/get-started/ and the Hetzner design and implementation plans in nebari-infrastructure-core, then review the examples/ configs. Document nic installation, the Hetzner validate/deploy/access/destroy flow, provider support, and the longer walkthrough while preserving the existing content under /classic/get-started/. Done means a new user can follow the quickstart to a working Hetzner cluster and the provider links and explanations are accurate.