homelab: scaffold unified CLI (registry, manifest, claim/release) in infra/cli

Begin evolving the existing infra/cli into the agent-facing "homelab" CLI
decided in the design/grilling session: one composable, JSON-capable surface
for the operations agents run over and over (mined from 51k commands across
2,225 past sessions; the infra inner-loop is ~29% of them). v0.1 targets that
loop — work/tf/claim — and ships here, in place, in infra/cli.

This first slice:
- command registry + dispatcher (longest-prefix verb matching) and a
  `manifest`/`manifest --json` progressive-discovery entrypoint; every verb
  declares a read|write tier so write-gating can be added later (everything is
  allowed for now).
- claim/release verbs wrapping the existing presence script (not reimplemented),
  with label-taxonomy validation.
- main() front-dispatches the homelab verb surface but falls through to the
  legacy webhook -use-case path verbatim, so the in-cluster infra-cli image is
  unaffected.
- fix a pre-existing vet error (glog.Infof missing format directive) that
  blocked `go test`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cli/presence_test.go

@@ -0,0 +1,24 @@
+package main
+
+import "testing"
+
+func TestValidateLabelAcceptsTaxonomy(t *testing.T) {
+	good := []string{
+		"stack:vault", "service:health", "node:k8s-node1", "db:pg-cluster",
+		"infra:gpu-operator", "host:proxmox-1", "pvc:dbaas/data",
+	}
+	for _, l := range good {
+		if err := validateLabel(l); err != nil {
+			t.Errorf("validateLabel(%q) = %v, want nil", l, err)
+		}
+	}
+}
+
+func TestValidateLabelRejectsBadLabels(t *testing.T) {
+	bad := []string{"vault", "stack:", "bogus:x", ":x", "stack", ""}
+	for _, l := range bad {
+		if err := validateLabel(l); err == nil {
+			t.Errorf("validateLabel(%q) = nil, want error", l)
+		}
+	}
+}