Move to a three-node cluster with a Talos VIP; add Longhorn

Every node is now both control plane and worker, giving real tolerance
for losing any single machine (etcd quorum needs 3, not 1). A Talos VIP
gives the cluster one stable address regardless of which node answers.

Also pre-installs Longhorn for replicated storage, backed by a Talos
UserVolume on each node's second disk (>=900GB, non-system) rather than
the default path — mirroring the pattern from the homescale repo.

Docs renumbered to make room for 06-longhorn.md; checklist, glossary,
network map, and CLAUDE.md's guided-bootstrap instructions updated to
match, including asking the user for node IPs, VIP, and disk info before
generating any Talos config.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -1,7 +1,7 @@
 # GitOps Starter Pack
 
-A minimal, real, working GitOps setup for a single Kubernetes cluster —
-built to teach, not just to run. If you've never touched Kubernetes,
+A minimal, real, working GitOps setup for a three-node Kubernetes cluster
+— built to teach, not just to run. If you've never touched Kubernetes,
 GitOps, Talos, or Argo CD before, this is meant to get you from a bare
 machine to a working cluster you actually understand, not just one you
 copy-pasted into existence.
@@ -35,6 +35,9 @@ shell history. This repo takes a different approach:
 5. **MetalLB** gives apps in this cluster real IP addresses on your own
    network — something a cloud provider would normally do for you, and
    bare metal doesn't have on its own.
+6. **Longhorn** does the same for storage — turning a spare disk on each
+   node into one pool of storage that's replicated across all three
+   nodes, so losing a machine doesn't mean losing its data.
 
 Git becomes the one place that's actually true. If you want the full
 picture with diagrams before doing anything, start with
@@ -46,13 +49,14 @@ picture with diagrams before doing anything, start with
 talos/    → Talos machine config + bootstrap guide (the OS layer)
 argocd/   → Argo CD install + the one manifest you apply by hand
 apps/     → Everything Argo CD manages from here on — demo app, MetalLB,
-            and wherever you add new apps
+            Longhorn, and wherever you add new apps
 docs/     → The numbered, progressive guide you should actually read
 ```
 
 ## Prerequisites
 
-- One machine (physical or VM) to become your cluster node
+- Three machines (physical or VM), each with a second disk ≥900GB, to
+  become your cluster's three nodes
 - `talosctl`, `kubectl`, and the `argocd` CLI installed locally
 - A GitHub account, and your own fork of this repo
 
@@ -68,11 +72,12 @@ Read these in order. Each is short — one concept per file.
 4. [`docs/03-installing-argocd.md`](docs/03-installing-argocd.md) — install Argo CD into the cluster
 5. [`docs/04-app-of-apps.md`](docs/04-app-of-apps.md) — apply the one manifest that hands control to Git
 6. [`docs/05-metallb.md`](docs/05-metallb.md) — give apps real IP addresses on your network
-7. [`docs/06-your-first-change.md`](docs/06-your-first-change.md) — edit a file, push, watch it deploy itself
-8. [`docs/07-adding-new-apps.md`](docs/07-adding-new-apps.md) — add something of your own
-9. [`docs/08-growing-up.md`](docs/08-growing-up.md) — next steps: more nodes, ingress, secrets management
-10. [`docs/glossary.md`](docs/glossary.md) — every term, plain English, for reference throughout
-11. [`docs/network.md`](docs/network.md) — the running log of every real IP address in your cluster, kept current as you go
+7. [`docs/06-longhorn.md`](docs/06-longhorn.md) — give apps real, replicated storage
+8. [`docs/07-your-first-change.md`](docs/07-your-first-change.md) — edit a file, push, watch it deploy itself
+9. [`docs/08-adding-new-apps.md`](docs/08-adding-new-apps.md) — add something of your own
+10. [`docs/09-growing-up.md`](docs/09-growing-up.md) — next steps: more nodes, ingress, secrets management
+11. [`docs/glossary.md`](docs/glossary.md) — every term, plain English, for reference throughout
+12. [`docs/network.md`](docs/network.md) — the running log of every real IP address in your cluster, kept current as you go
 
 Prefer a single condensed list you can work through step by step with
 Claude, checking items off as you go? Use
@@ -101,7 +106,7 @@ moving on.
 
 This repo deliberately does **not** ship ingress, TLS/cert-manager, or
 secrets management in v1 — they're real next steps, documented in
-[`docs/08-growing-up.md`](docs/08-growing-up.md), left out so the core
+[`docs/09-growing-up.md`](docs/09-growing-up.md), left out so the core
 loop stays small enough to fully understand first. This repo is also
 **public** — never commit plaintext secrets, credentials, or private keys
 to it; see that same doc for how to handle secrets properly once you need